I like rainmaker the most because you're in control of how quickly you can win or lose. Splat zones is a close second. Some weapons are pretty broken on tower control....
Camp Triggerfish in zones is my favorite rotation EVER! I rock the N-Zap '89 and I block area above the opponent's spawn by using decoy sprinklers. I once got 23 kills. Also, zones in Blackbelly Skatepark is pretty hardcore.
Agree with everyone saying it depends on the map. Pretty much every mode is horrible on some map, and amazing on some other map. That's the unfortunate part of having every mode available on every map though, unlike other games where usually only some modes are available on certain maps.