Is this a tier list of how good they are at rioting, how hard they are to counter or how flexible they are?
Because those are all very different questions, for instance Reaver is great at killing raiders that come at it but that's all it can do.
While Crab is a solid assault-skirm.
Ogre, in contrast, is awful at killing lots of chaff at low densities (and can indeed be easily killed for cost by microd glaives) and it's low hp and high cost make it very vulnerable to Phantoms and Lances, but it is a fairly good generalist, able to do a mediocre job in a variety of roles.
From the looks of your list you're asking how good a generalist they are, in which case I'd still say that Ogre above Crab is nonsense.
I also assume you're talking pot-only which is why you have Archer and Venom in B rather than S.
Corsair F-tier?! The unit with raider speed, assault hp, riot range and raider dps? That can beat hover with monospam? That Corsair?