Mmm, middle of the road, I'll vote Chuck.
Casey vs Jeffster should be a whole lot wilder and more hilarious than it was in this episode. Sorry, my interest in men's haberdashery is severely limited and my interest in Subway sandwiches is not much greater.

Maybe Jeff & Lester will decide to launch a jihad against Casey despite the supposed truce.
That should be good.
As for Chuck's story, wow, the logic is getting tied in knots. Chuck dumped Sarah because he wanted to be A Real Spy(TM) and now he needs to become A Real Spy(TM) so that he can win Sarah back? Being a spy supposedly means you can't have a real life, and now it's the only way he
can have a real life?
Sooo...why can't Chuck and Sarah just call up General Beckman and just resign from the CIA? Don't tell me that people aren't allowed to do that! Of course they can.
And Chuck better resign because it's ludicrous that he ever thought he could be A Real Spy(TM) without being willing to kill. Even police officers have to be willing to kill! Now Chuck is compounding the lie by making Shaw think he can kill. Guess what, his next gig will be another assassination. Does Chuck expect Casey to follow him around like a homicidal Cyrano de Bergerac and do all his killing for him? I'm sure Casey would love that, but it does seem wrong and also extremely illegal and likely to get them both thrown into prison.
Another problem: Chuck's aversion to killing seems to be simply personal inhibition rather than based on morality. Otherwise, he shouldn't be any happier about Casey killing the guy than he would have if he'd pulled the trigger. Makes it hard to sympathize with his position. If he's willing to be friends with killers like Casey and Sarah, he shouldn't have any personal objection to killing, assuming the target is a legit evildoer...
...which leads to another problem: Why didn't Chuck balk at the idea of the CIA killing American citizens without any whiff of due process? How does Chuck know the guy was guilty? How does the CIA know the guy is guilty? He's on US soil - why can't he be arrested and prosecuted? Assassination should be a tactic reserved for al Qaeda outside of US jurisdiction where due process isn't a realistic option. The behavior of the CIA in this episode is downright disturbing.
Odd- with the intersect still in his head, I would think the government would be reluctant to let Chuck just walk away, but he's told, "pass the test, or you go back to your old life." Just like that? Seemed very odd to me.
Yeah...in order to extend this thin premise to a third season, the writers are twisting the logic in knots. Being booted out of the CIA would be the best thing that could happen to Chuck. Sarah resigns, they live happily ever after, the end.
Even if Beckmen were lying about booting Chuck, it's Chuck who should realize he need to stop pursuing a job that is completely wrong for him and resign. At that point, if Beckmen is bluffing, we'd find that out.