Robert is a little nasal sometimes, and he is not super perfectly clean like Tank.
But Tank does not have the man power and grunts like Robert. And his runs are a little to whimsical sometimes, Robert gives you nice authentic old school runs.
Tyrese is great but he can't go very high, and he often sounds like he is about to die.
Anthony is a brilliant singer, but his tone, I can only take it so much.
John Legend be doing the same thing over and over and over. His voice is always so heavy and slow.
Sisq?'s biggest minus is he can't really give a sweet soft vocal, and work just on tone... And he can't produce super clear notes, like Tyrese struggles to do apparently...
Usher must have the most boring forgettable voice of them all. It just does nothing for me, even prefer a Ginuwine vocal. Usher has no soul to me... I think the only vocal I enjoy by him is his cover of Phil Collins' "You'll Be In My Heart".