I love gravity control - making enemies your toys, summoning junk from god-knows-where and firing it off - it's great fun! In a fast paced environment, its longish animations and less flashy graphics means you don't get to appreciate it if completing missions as fast as possible is priority #1.
Similarly, I think energy blast has some some of the coolest, most iconic animations among the various blast sets, but I do not like the unpredictability of the knockback and having to "waste" a slot to make it knockdown instead.
From a slightly different perspective, I enjoy playing masterminds, but in end game content, I seem to play the role of "cannon-fodder-dispensary" or fall back on my secondary set, more than I am able to enjoy commanding my minions to wreak havoc upon my enemies...