smart all the way! I recently made the switch, and although calls dont always go out, its usually BTL numbers i'm trying to call. Smart holds onto your number forever, you never lose it. Moreover, if someone steals your phone and you've reported it stolen, it will be locked. when that person goes to smart to unlock it, they confiscate the phone and let you know so you can get it back.
there's a reason they call it "SMART!"