If I have to rate the WORST, it would probably be:
Light of Doom - Just ludicrous
Dot Dot Dot - Stank Stank Stank
Rocket - As has been said, girl groups need to be better than guy groups to get noticed. These girls are worst than at least 3/4 of the "guy groups" on this ONE show though, not "better" as they need to be. NO charisma. And pretty lame skills.
The Hatch - BOOOORING.
Any of these four could go and I won't even blink.