The Genius Cavimanus for sure! They have Virtual 7.1 Surround Sound, which is GREAT for FPS games and MMO games, HECK it's great for all games AND movies! The only downside would be that they have a 40mm Driver over the SteelSeries Diablo III which have a 50mm, but there shouldn't be a huge differnce in bass, also they have the same size driver as the G230's which means that they will give you practically the same bass.
To over simplify, get the Genius Cavimanus as they have just as good of bass if not better than the G230's and have 7.1 Surround Sound (which should help you hear footsteps and help you decode where they are coming from exactly.
Have fun with the new headset!
~Upstagebuffalo