I like departing from either port and have been out of both multiple times this year. For airports I prefer MIA to FLL usually because I have more flight options from MIA plus FLL has the no more than 4 hours before flight check in rule which can make it more than a bit of a mess landside on busy cruise days. You can use either airport for either port.

Unless everything else is the same, I wouldn't use the departure point (between those two choices) as a reason to choose a particular cruise. I would look at itinerary and ship before looking at departure point.