Southern Florida is too broad a term for anyone to give you really good advice. Have a look at some service maps. That should tell you pretty quickly what to go with. Also, keep in mind Tmobile doesn't force you into a contract while sprint will. Assuming you have a handset currently which you could get unlocked, you can try tmobile out for as cheap as $30 for the month. This won't be unlimited data, but you will be able to Gaige whether reception is adequate for you or not and then upgrade to another plan.