I can't speak as to which service provider you should go with, but as far the phone goes-- yes, it's a great device. I have heard others talk about how the Bionic had some issues. I think battery life was one, right? I can easily get through 15 or more hours with moderate use in a day. Software side, it's very stable and has some nice features that you may or may not decide to use. I did go with a 3rd party launcher, Nova. I would get annoyed fast if I had to use the stock launcher, but that would go for any non-vanilla Android device.
At the moment, the S4 and the HTC One are the top devices in Android land. So yeah, you definitely can't go wrong with the S4.