AT&T, Sprint, and T-Mobile will work fine, since they all offer service in Puerto Rico as part of their US national networks. MVNO's on those networks should work fine as well.
If you have an older T-Mobile handset (OLDER - like pre 2007/2008), your data usage may be slower than in the US.
Verizon may work depending on your plan, but they left the PR market completely in 2007.