I'll just quickly give my thoughts on all the candidates fired so far.
David - It was obvious from the first minute that he was totally out of his league. Did he deserve to be fired over Sam? Eh, probably. The ideas that Sam was suggesting were just ridiculous, but at least he was actually doing something. David, you hardly even noticed he was there.
Jason - Not a terrible leader by any means, but he made an insanely stupid move by deciding not to bother meeting with the customer, and just producing whatever the hell he felt like. The fact that he got cut to ribbons by Nick and Sam in the boardroom was the icing on the cake.
Sam - Wow. Just... wow. Did he even exist in the same world as everyone else? And what the hell was up with that look he gave Trump at the end of the boardroom?
Bowie - Maybe a little unlucky to be fired for not fully getting behind a strategy that was never going to work anyway, but I don't think he'd have got very far regardless. I think both he and Kwame were equally deserving of the chop, to be honest.
Kristi - I can see what she was going for with that "big risk, big reward" strategy, but it flopped spectacularly in execution. Even if Omarosa did deliberately lose that money in order to get rid of Kristi (and I can't think of any sane reason that she would, not that "sane" is a word I'd ever use in association with her), Kristi just made way too many major blunders.
Jessie - I don't think there was necessarily anything wrong with the way she handled Omarosa's insults, Trump shouldn't have called her up on that. That said, I actually do think she deserved to go, as she was the weakest member of the losing team, and arguably even the weakest candidate left in the whole game.
Tammy - Looked like a real contender in the first few weeks, but really fell apart after the teams were mixed. That said, the reason she was fired was silly. Katrina was definitely a stronger candidate than Tammy overall, but she was completely responsible for the team's loss, and her attempts to blame Troy were just pathetic.