In my experience, Sun rims offer a lot of bang for the buck while Mavic seem to be on the high end for what they offer. When I build wheels with both brands they tend to last the same amount of time, so guess which brand I choose? The quality of the wheel build is going to be what matters the most here, so make sure you get someone who knows how to build a good wheel (if you don't know how yourself). The Sun is a bit lighter if that matters to you.