Favors is definitely the better option to defend Tim Duncan 1 on 1. Since this is a team game, you also have to think about what the Spurs would do. I am a Spurs fan btw. The Jazz need to figure out a way to keep Favors guarding the paint. He is easily their best shot blocker. The Spurs play a lot of pick and roll when Parker and Duncan are on the floor with Duncan setting the screen on Parkers man. This will draw Favors outside of the paint and Parker won't have much contesting presence at the rim if Favors isn't quick enough to cover Parkers drive. He could also get stuck on a switch and left guarding Parker on the perimeter. With Bonner/Diaw also on the court with Duncan (they are both have 3pt shots that a defense has to honor) it sucks the second big out of the paint and there is no shot blocking left inside. That is the same problem that the Lakers were having with the Spurs offense. Bynum couldn't stick with Parker on the perimeter, Gasol was reluctant to help because his man would shade out to the 3 pt line, and the play would also leave Duncan wide open from midrange at the FT line (He has been hitting a ton of those this season).