So, Warframe is still heaps of fun, playing it a fair bit really, and wanted to write some more about it here. I decided to rate the top perceived warframes in terms of usability and potential group function. Obviously this will be subjective, but at some level it's quite useful in terms of which frames to go for and to put in your arsenal as soon as possible.
Essential Warframes (Alphabetical)
Enables any difficulty Defense, Mobile Defense and Excavation to be handled without too much difficulty.
Stealth is blatant cheatery, this frame makes quick running missions a breeze, can also be group utility when specced for radial disarm at higher levels, as bombards without their rocket launchers aren't as dangerous as their armed counterparts.
Although a very narrow minded character, this character is the only one that enables you to do any survival mission up to the higher durations without too much effort. Hydroid can also perform this role well, but that requires a sane group.
Makes everything easier by slowing down all the enemies when you want them to be slowed down, or speeding them up with different mods for efficiency in survival/defense.
Two different builds for two different scenarios. Trinity can supercharge your group by feeding them constant energy, enabling abilityspam beyond sanity. The other build is the invincible tank, where you link up with enemies and redirect damage to them.
Enables complete safety for melee-defense or survival even at high levels with the swirly vortex trapping mobs.
I feel that if you have these frames and the mods to go with them, you can enter any 3-man group and tackle *any* mission with relative safety and sanity. Other frames will likely do a similar job, but I feel these are the most versatile of the group, so, if you're a team player - aim for these frames initially!