From my understanding, Banshee is B ties only because they both start with B, but by that logic she should be in Belongs in the Trash tier

Baruuk should be at least A for reasons i stated in another comment

Gauss can be immune to every single damage type the Void and the Grineer throw at him with the only exception being Toxin, while also being immune to CC and making tons of guns viable thanks to reload and fire rate buffs

Revenant trivializes Kuva lich content and fights against the Lich and is the best Index warframe, while also being the only warframe that can reliably one shot kill any enemy with abilities alone (Reave on a Thrall with enough power strength will deal more than 100% of their EHP as damage, doesn't require a max strength build), with exceptions made for enemies with damage reduction and bosses

I take you're also including Primes along with the normal version so... Atlas Prime has the third highest EHP of all warframes behind Grendel and Inaros, but those warframes can be immune to CC only with mods, while Atlas is immune to everything, even pushes and pulls, so he's really great in Disruptions, where accidentally getting inside a nullifier bubble can mean instant death because of loss of endurance abilities

Titania is the best Archwing in the game, and there's a reason it's limited to ground missions only, can also be by far the fastest frame in the game (except max range nova, but she works far less in closed areas). The only frame that can use its exalted weapon to kill Eidolons for how powerful it is.