What are your squadmate rankings based on how they help you beat Insanity? (My personal rankings)

[z00m]

I will say that it does depend on what class you are using and every squadmate is useful in some way but I do think some are much more reliable than others. Also, I am not including DLC exclusives. The classes I usually used in order were Adept (1), Sentinel (2), and Sentinel (3).

Mass Effect 1:

1. Wrex - He has the highest health in the game and has both biotic and combat abilities.
2. Liara - Has the best crowd control abilities in the game especially her singularity.
3. Kaiden - Similar reasons with Liara but his crowd control and disabling abilities are not as efficient in dealing multiple enemies as singularity. But neural shock is seriously underrated especially since you can use it against charging krogans and rachni soldiers.
4. Garrus - Does good weapon damage especially with sniper rifles and is great in disabling guns and tech abilities.
5. Tali - Definitely the best against robotic enemies like the geth but she honestly struggles against organic foes. I remember bringing her to Feros and she was useful until the Thorian creepers and things went south where she basically replaced Wrex as my usual cannon fodder bait.
6. Ashley - I know I previously mentioned how every squadmate is useful in some way but Ashley in ME1 feels like the black sheep here. She is all about weapon damage and combat abilities but that is pretty much it. She feels redundant by Wrex and Garrus who have her abilities but with extra biotics/tech uses. Sure she can help you outgun the enemies faster but I find it preferable to have abilities that make an enemy helpless rather than trying to kill them with sheer firepower and risk getting overwhelmed.

Mass Effect 2:

1. Kasumi - In my opinion, the best squadmate in 2. Her shadow step can do quite a lot of damage even against armored enemies but her flash bang is the best ability in the game. It stuns protected enemies, knocks unprotected ones down but the best part is that it can shut down biotic abilities including Harbinger. In fact, you can use her flash bang on Harbinger, run up to him, and melee him to death. She is my main squadmate for Horizon and the Collector Ship levels. She does struggle in scenarios where you are getting swarmed by multiple charging enemies though.
2. Grunt - He is the best against charging hordes of enemies due to his krogan tankiness. And he provides armor shredding support with his incendiary ammo and concussive shot knocks down enemies or bypasses biotic barriers. He and Kasumi are my main squad composition against Collectors.
3. Miranda - Really versatile in having warp and overload against barriers. Plus she provides squad damage bonuses.
4. Thane - Like Miranda, he also has warp in dealing with armor and he gets to carry a sniper rifle. His ammo power is underrated as it helps you kill unprotected enemies quicker.
5. Zaeed - His disruptor ammo is too reliable in dealing with shielded mercenaries and synthetics. In fact, he is my main squadmate in dealing with geth and drones. Also, he carries a sniper rifle and I usually like to pair him with Thane.
6. Jacob - I used him quite a lot during the first half of the game. Even though he is basically a less tanky Grunt, he doe provide opportunities for biotic combos with his pull. In fact, I consider pull a better "shut up" move than concussive shot.
7. Samara - Her reave is extremely useful against armored enemies especially scions. I actually consider her the best against scions but her other abilities do get mitigated by barriers.
8. Garrus - Sniper rifle and barrier piercing capabilities. Although I do prefer Zaeed and Thane over him.
9. Legion - Useful against synthetic enemies like the geth and carries the best sniper rifle in the game but his abilities don't provide much against other types of enemies but his combat drone is a good distraction and can drain shields.
10. Mordin - He is useful against armored organic enemies especially with his Inferno but I feel like that is pretty much it. Also, neural shock does not feel as powerful as in ME1.
11. Tali - Has the same abilities as Legion. But she is less durable and decides to carry around a shotgun. I honestly prefer Legion over her.
12. Jack - Both biotic abilities are mitigated by barriers and you are honestly better off having warp ammo as your bonus power. She is not useless but she feels heavily outclassed.

Mass Effect 3:

1. Garrus - They really weren't kidding about Garrus Ascending to Godhood. But I did not use him as much until I finally bought the N7 Typhoon.
2. Liara - The ultimate combo starter especially with her singularity. A lot of my gameplay was basically singularity into warp/reave/throw.
3. James - Same as Garrus but his other abilties are not as spammable as Garrus's or Liara's.
4. EDI - The tech counterpart to Liara in terms of relying on combos. She is great against Cerberus and actually decent against armored reaper enemies especially with my favorite combo: Inferno into Warp. But since Inferno has a higher cooldown than singularity, the combo is not as spammable.
5. Javik - Basically, Liara with an assault rifle. He does have 2 biotic abilities to chain combos but they do not feel as efficient as singularity. Also his dark matter drain is useful against armored reapers but I feel like he struggles against geth and Cerberus troops.
6. Ashley - Big improvement from ME1 especially since she can make combos on her own with disruptor ammo and inferno grenades. But I prefer the incendiary ammo support from James.
7. Kaiden - Has decent abilities against shields and armor/barriers but nothing too special.
8. Tali - I honestly do not like putting Tali low for all 3 games. She is good against geth, can keep herself alive with energy drain, and her drones provide vital distractions but she does not have a lot of combo potential as the other squadmates. I really love Tali and even used her in the final mission because of romance but gosh, Garrus was basically Iron Manning that finale.

Honorable Mention: If he was not DLC, I would put Wrex at #6.

In the end, this ranking is based on my opinion and experience when beating all 3 games on Insanity difficulty.

[valium]

ME1: it doesnt really matter who you bring, they are all pretty much the same in terms of effectiveness, just bring whatever covers what your class is lacking.

ME2: Miranda is the best, she can deal with both barriers and shields, and boosts Shepard's damage, that puts in more work than any of the other squad members can muster. Then it is anyone who isnt Jack. Since half the game is loyalty missions, it usually ends being Miranda + loyalty mission person.

ME3: similar to ME1, no bad teammates, they can all be built to be absolutely broken, with Tali having the lowest high-end. Use whoever covers what your class is lacking, or combos with your class.

[globo]

In ME2 Kasumi + Miranda was my favorite combo and like valium said, the others were "loyalty mission person".

In ME3 Liara + EDI cover all my needs.

[barzai]

I have no quarrel with your assessments but I am a roleplayer not a minimaxer, so for me it's all about the banter, the interactions, all that stuff rather than "how can I create the most effective party in combat?"

Personal view: if all you ever do is consider your teammates as tools in your toolbelt you're missing out on a great deal of what makes these games Hall of Famers.

[z00m]

I do try to diversify my squads for each mission and see the interactions. But there are times where I had to restart missions and pick my same usual squad members since I also do not like dying so many times.
Ex. Miranda and Garrus to Collector Ship Level - Died Many Times - Switched to my usual comp: Kasumi and Grunt.

[Shadow]

Me1:
1. Garrus
2. Kaiden
3. Liara
4. Wrex
5. Tali
6. Ashley

Mass Effect 2:
1. Jack - I love shockwaves she is the best in every situation except geth
2. Garrus
3. Grunt
4. Legion
5. Tali
6. Samara
7. Thane
8. Mordin
9. Kasumi
10. Zaedd
11. Miranda
12. Jacob

Me3:
1. Garrus
2. Liara
3. Kaiden
4. EDI
5. Tali
6. Javik
7. Ashley
8. James

[Ma77i7yahu]

I play as a sentinel, so my preferred squad would be Liara and Tali for ME1; Miranda and Samara for ME2; Liara and Javik for ME3.

Having said that, I really just pick whoever across the missions as I don't really need assistance in any of the games so it doesn't matter from a combat or support perspective - almost all of them have the capacity to knock down or prime an enemy for a biotic combo anyway. I do pick certain squad mates for certain missions where it makes sense to do so from a story perspective.

[ᚣᛖᛁᎶ]

ME1 - Garrus and Wrex, simply because they are the most interesting companions with some cool banter. The scene with them on Noveria if you kill the Rachni queen is hilarious. Like others have said, squadmate choice doesn't seem to matter that much in 1, as long as you have someone to pick locks you can just use whoever you like the most, as the game requires very little tactical thinking.

ME2 - here is where I'd have to divide them into tiers:
S tier:
Grunt - AMAZING tank, and you really can use one in the early game on insanity, gets an endgame shotgun right off the bat. Even if he falls off a bit late game, he pretty much carried me through early-mid.
Garrus - Overload, concussive shot, AP ammo, sniper rifles. A bit squishy but a great DPS.

A tier:
Miranda - warp and overload, plus a team damage buff, but not much weapon damage of her own. Also squishy.
Legion - a bit biased here because he's one of my favourite characters, but I found the drone to be extemely useful for distracting scions and harbinger, and the widow rifle gives him good DPS.

B tier:
Zaeed - nothing spectacular, but he has good weapon dps and is pretty tough. Kind of a worse Garrus.
Samara/Morinth - I'll be honest, I never use these two very much, but neither has anti-protecton abilites by default and throw/pull's usefulness is limited in 2. Samara is probably better due to unlockable reave. Also, they can use ARs so their DPS isn't too bad.

C tier:
Tali - a squishy squadmate who specialises in shotguns, what could possibly go wrong. The drone and energy drain are pretty useful though.
Mordin - good v armour but not much else.

F tier (skipping D and E):
Jack - outside of insanity, her abilities are more support oriented, and on insanity they are completely useless. Warp ammo is good but not worth wasting a squad slot on.
Jacob - just rubbish overall. Squishy, no useful abilities, shotgun specialisation. Even his unlockable ability is just a copy of Grunt's.

Not mentioned - Kasumi because I didn't use her enough.

Edit: and I realised I forgot about Thane. He's not someone I use much, but judging by his abilities and weapons I'd put him in A tier for most difficulties and B tier for insanity because of the shredder ammo.

ME3 - hard to rate because there are no bad squaddies, everyone has their use. So I'm not even going to try.

Of course, this is all my personal subjective assessment and blah blah.