What's worth getting from each syndicate?

[Normal Lee]

As far as mods go, at least. I'm getting close to MR12, so pretty soon I'll start farming up New Loka to get that sexy Sancti Tigris, but before I start making the transition from the two syndicates I'm already in (Steel Meridian and Red Veil), are there any mods that I should make sure to grab before losing standing?

I don't have near every Warframe yet, nor most of the weapons that some of the mods are for, so I have no clue which would at least be nice to have.

From SM, I currently have:
Scattered Justice
Firequake
Chilling Globe
Antimatter Asborb
Escape Velocity
Regenerative Molt

From RV, I currently have (discounting duplicates):
Eroding Blight (didn't have any of these weapons and so I just chose a random one)
Hushed Invisibility
Irradiating Disarm
Jet Stream

I've tried looking up which syndicate mods are worth getting, but most of the advice I see is outdated and/or differs from what I know just from absorption of other people talking about builds.

[SwitchBlade]

U should first try getting both of the weapons thye have instead of mods. Then AFTER you get the weapons buy mods or the syandana

[Shadowy The Insane Bovinemancer]

If you plan to buy warframe/weapon augments, then buy The augments for The warframes/weapons you like to use.

[Vulpesrojo]

If you haven't gotten the syndanas from RV/SM, then get those, as there is no way to trade for them. If you are a completionist, also get the sigils, as those are tied to ranking as well and can only be gotten through them. Next would be the RV/SM weapons (Rakta Ballistica and Cernos, Vaykor Hek and Marelok), as they are expensive otherwise. After that, the Large Team ______ Blueprint, as they can only be found here. Next, get the Weapon Augments, as they are tied to only one Syndicate. Finally, any warframe augments that will not be covered by the new syndicates come last. IF you have syndicate standing left (probably in the forms of items), get Mods covered by your new syndicates, and void key packs.