Teams where Kaep would be an obvious upgrade over the current starter;
Jets
Dolphins
Browns
Bengals
Texans
Jags
Indy (Until Luck returns)
Giants
Bears
Vikings (Until Bradford is cleared)
Cards
49ers
He's also not decidedly worse (not necessarily better either) than Flacco and Tyrod. He would be guaranteed the first backup on every team except the Pats and maybe the Packers depending on how good Hundley actually is. He makes TOO much sense as the Seahawks, Panthers, or Bills backup since those are all mobile QBs that Kaep can at least emulate and keep most of the offense in tact.
There's no way anybody can be genuine about Kaep not being "good enough" to play in the league. If you don't think he's that good that's fine, but you can't deny he's better than guys like McCown or Hoyer, and he's definitely better than older guys that can't go anymore like Palmer and Eli.