I think I've seen every Looney Tunes cartoon in my short life span. I always preferred WB to Disney, Bugs to Mickey, etc. The best ones are, obviously, the Chuck Jones shorts. But which of those are the best?
I think the answer must be "Ali Baba Bunny". It has the famous Bugs and Daffy rivalry, it has a different setting, it has a hilarious new character (Hassan), it's just cartoon perfection. Also has some of the best damn lines in any Looney Tunes cartoon.
"Open sasparilla? Open Saskatchewan?"
"I'm rich! I'm wealthy! I'm comfortably well off!"
"DUCK. YOU HAVE DESECRATED MY LAMP."
Classic. Absolutely classic. No cartoons will ever match the genius of the Looney Tunes Chuck Jones ones.
The animation is also top notch. I hate seeing a Looney Tunes cartoon with bad animation, but Jones never disappoints. The little things in the animation just make it perfect, like when Daffy first spots the treasure, and his bottom bill shifts side to side in greediness, or when Bugs is surprised by Daffy shouting for help, his toes scrunch up...
Long live Bugs Bunny.