anjroo is right. It's impossible to pick one favorite show. I haven't even seen them in a while even though they're on every day on some channel or another.
Every show, although about "nothing" , has at least three funny subplots going on.
I liked the one where Jerry and Elaine decide that they can do "the this" and "the that", or be friends and have sex too. But that one just popped into my head, not favorite.