The best episode was the one where Ari completely rips apart Josh Weinstein (
YouTube link, contains NSFW language). Actually, any episode where Ari launches into a huge angry rant is pure gold (no pun intended).
Any episodes that don't feature Ari in a prominent way are not really worth watching. I wish there was a spin-off show built around Ari, Babs, Dana Gordon, Lloyd, and Mrs. Ari. The antics of Vince and the boys never really interested me.