Sense is the most visually appealing. Blur causes the least headaches for developers. I don't have enough experience with Touch Wiz to make a fair assessment.
(what am I talking about? well, goto the market, notice how the release notes for an overwhelming number of applications say something to the effect of "updated to fix bug caused from Sense UI related phones" some devs even go as far as pleading that you stay away from them all together)