In terms of accomplishments Rios has the bigger titles and was ranked number one. However, I think it's safe to say he underachieved given his immense talents.
Gonzalez, I think it can be safely said, overachieved through hard work and the willingness to listen and learn in order to improve as evidenced by his hiring of Larry Stefanki which led to the best results of his career.
Of the two Gonzo was certainly more well liked among his peers and tennis fans and seems an overall good guy. Rios, was and is, a jerk. It's too bad that age hasn't mellowed him but that's what makes him Marcelo.