It all depends on what we have to give up for him. While Cesar isn't a great upgrade he is a player who has yet to come into his prime, while AGon is actually in the 2nd year of his prime and has yet to show any significant increase in skills, and actually showed a dramatic drop off in the first year of his prime.
Don't get me wrong I'm fine with AGon, but if we can get Cesar on the cheap, I'd at least consider it.