I don't see one or the other as a "better player," rather as both having different skill sets.
Rhodes is a guy that can step back and demand to be guarded from 15 feet. He's athletic, can run and dunk, adequate passer, but has a more slight frame that can be overpowered by the bigger players underneath. He's also very long so, even when tightly guarded by a bigger man, he can still get his shot off.
Curtis is a guy that likes to get it on the block and work angles under the basket. He can hit the 13-15 ft jumper, but its not a skill he likes to use. He would rather push you into the paint or spin off you and use bank shots. Because of his size and strength, he's rarely out of position on rebounds and has a good sense of where it will come off, both of which allowed him to lead the nation in offensive rebounding. He's an adequate passer. His size is somewhat limited to his body, as he's not long-armed like Rhodes and Varnado.
Of course, Rhodes is more tailor-made for the NBA game and Curtis is more of a guy that excels in college, but doesn't the skill sets that the league is looking for.</p>