Said the two things i was coming in here to say so...
nikkas in here arguing shyt that is subjective(who sings better) when this thing really just boils don't to numbers. I've said this forever and i'll say it again...when it comes to anything black in America, black ppl make things popular but white ppl make things successful. Save your hate mail if you disagree, it's all about numbers. When white ppl jump on something popular in black culture the success and popularity goes thru the roof.
Also Usher has always had a POP slant to all his songs at least since the My Way album which catapulted his career. I also would agree with song selection(Usher had a more mackish vibe while Ginuwine came more raw and raunchy initially) and image being a factor (Usher looking and sounding younger and smoother in his vocals than Ginuwine). In my opinion there's literally nothing Ginuwine does better than Usher other than dance, it's just to bad singles don't sell off dancing alone. Ginuwine came with his biggest hit out the gate and didn't have anything even close to it after that, while Usher was cranking out hit after hit...pop type hits at that, ie that crossover game was.
End of the day Ginuwine stayed more of an urban star, which is why i suspect nikkas ride with him more and Usher sound had more crossover appeal that would eventually turn him into an international superstar.