What was the best class for insanity again?

[Grantorino]

I think I might run femshep again.

[Synavix]

I've seen lists that put almost all of the classes as the easiest depending on which ones the person liked more. I've only played 4 of the classes on Insanity in ME2 but these are my opinions:

Soldier/Infiltrator are just really solid choices and should be pretty easy because weapons are extremely strong in 2 compared to the other games. Adrenal Rush or Tactical Cloak help you stay alive while killing enemies faster.

Sentinel gets VERY easy near the end of the game with Assault Armor and your passives leveled up. You can basically just walk up to any enemy and 1v1 shotgun-to-the-face. They'll burst your tech armor which will make them stagger or fall over, and you just finish them off, put your tech armor back on, and move on to the next target. But I personally found the class to be really annoying early on. Not necessarily bad, but like a weaker version of the adept or a significantly weaker engineer. I imagine that Vanguard is the same: weak early on but very strong late game.

Engineer was probably the strongest class for me, but I think it depends on whether or not you have DLC weapons. The Locust from Kasumi's DLC is pretty good early on, but then you want to train for ARs when you have the chance and get the Mattock. The Mattock is so much stronger than anything else it's crazy. Area Overload or Area Incinerate on any enemy to destroy its armor, then one burst of headshots from the Mattock will kill almost anything. Then you just sit behind cover until your powers come off cooldown again. The class kills things very fast at that point, and it completely destroys Scions, which are one of the hardest enemies in the game to deal with on Insanity.

Adept is kind of similar to Engineer for playstyle. I think it's a very strong class, but one of the more challenging on Insanity because your crowd control doesn't do much. I didn't have the Mattock DLC when I play this one, but the strategy was the same. Stick to cover and learn to bend your biotics around corners, use Locust + Mattock (once you train ARs) if you have them. Use your squadmates as distractions to keep yourself alive because you're really squishy. The problem with Adept on Insanity is that it requires too much setup, so it takes more time to kill things, which = more time to mess up and die. Probably my favorite/most fun class though, especially going into ME3.

[budisourdog]

Soldier's Adrenaline Rush + the Semi Auto Sniper Rifle = Free Headshot kills en masse
Solider is the most versatile class being able to use all the weapons and slow time

Engineer is pretty strong if done right, Incinerate is your best friend against Organics and Armored Synthetics, Overload can take down biotics and shields, weaponwise a lot of people tell you to use the Locust however in my experience the SMG you get when recruiting Tali forget its name puts out loads more damage quickly and is accurate at range when fired in bursts, pistol is good for breaking through armor and I usually pick up sniper rifles to expand my ranged and armor breaking capacities.

Sentinel is another great choice with tech armor, overload, warp, and throw, all useful abilities plus with tech armor you don't need to get Geth Shield or Barrier as a bonus power and can try out the Flash grenades or an ammo power if desired.

Infiltrator, Adept and Vanguard I don't have much experience with, but vanguard charge strikes me as suicide for insanity if you aren't being very careful tho maybe I'm just terrible at the class.

[Black Hole]

I found soldier to be the easiest class to use for tanking stuff, but I prefer engineer or adept myself as I like their abilities more.