Hold It Against Me. BY FAR!
Both are mindless dance songs, yes, but Enrique's song reminds me too much of a Jersey Shore anthem. And anything that reminds me the lowest common denominator of human trash doesn't rank high with me. Besides, I really don't think Enrique is a great vocalist. If anything, he's the male equivalent to Shakira: a unique warbler with that spanish flare that many think is sexy, but really is just as annoying as a goat's heehawing. I may be in the minority, but I actually like Britney's voice. Sure, it's not Mariah Carey, and she's not a real vocalist by any stretch of the imagination, but its pleasant and I find it quite sexy.
Brit Brit's song might not be the most innovative song on the market, but it's far superior as a song. That dub-step breakdown alone sh*ts all over anything Enrique has put out.