I like complex arena's, but the problem with ASB is that matches take quite a while to finish. Plus, you've got more then one match going on at the same time, so I tend to forget some banned-moves/special-added-arena-effect/etc. Which makes general arena's more attractive for swift battling.

Or maybe that's just me being lazy =/

Actually, I think I have the simplest arena out of the gymleaders.