I legitimately think there is an answer here.
Bieber isn't exactly my style, but I'll admit he's got a solid voice, and his drumming is pretty damn decent.
One Direction is filled with guys who did well on national television specifically for their voices. Their music is admittedly really catchy, and they all have great voices.
Nicki Minaj... Well, she's annoying as fuck, but her rapping is good. On top of that, she's pretty hot outside of her scary face. Though I know most of you will disagree with me there.
Lil Wayne is just awful. I've yet to find a redeeming quality in him. So, ultimately, I'd go with D.