I don't ride Western, but if I did, I'd be barrels, poles and cow work. Nothing quite matches that adrenaline rush you get when you're doing the (under control) speed stuff IMO, and cow work would just be an extension of that.
As an English rider, I ride jumpers and eventing. If we had h/j and eq over fences in Australia I'd be into that too. We do have prix caprilli dressage tests here but I've never been lucky enough to watch one, let alone compete, which is a darn shame really because I think it would be fun.