Batman: The Animated Series for me. I'm a fan of art deco and 1940's fashion, and this show had it in spades. It even had the classic mobsters as minor villains/cannon fodder, complete with fedora hats and Tommy guns. Admittedly, the retro visuals are a bit hard to reconcile at times with subsequent DCAU shows that feature more futuristic aesthetics and technology.
By the same token, I liked how the show was grounded in reality more. Personally, I feel Batman is at his best working alone in Gotham fighting rogues with ambitions no greater than wreaking havoc on the city. Most of my least favorite episodes were when some super powered villain showed up or that pretentious dickhead Ras' Al Ghul showed his ugly mug. Leave the world-ending threats to Superman, thank you very much.
Still, Batman: TAS represents the quintessential Batman experience for me.
Batman Beyond was also an awesome show. I applaud the creators for not phoning it in just because the concept for the show began as an excuse to sell toys. Terry McGinnis is a likeable kid and a worthy successor to Bruce Wayne. I also appreciate how they utilized the futuristic setting to tell new stories and situations rather than rehash old material all the time.