Google
tank vs tankless water heaters and it should be a very informative read. I would steer clear of the propaganda sites and stick with the various reviews from average Joes.
But I would consider
Laurentiu 's advise and consider a solar heater with a tank heater backup. I do know the electric tankless require a ton of instantaneous electric (to the tune of 14kW) for a larger house, and the gas tankless is nearly even in efficiency to a gas tanked heater, giving you a ROI of nearly 22 years according to one article i read. There are also water heaters that make use of otherwise wasted heat from your heat pump, which I'm certain you'll be using in Florida.
OMG I just found out about a great combo, a tank water heater that uses a heat pump! I'd heard about the ones that use the heat from the home heat pump, but
here's one that is a stand alone system. A heat pump is inherently more efficient than a resistance coil in that it simply moves heat from one point to the other. This site
from the Energy Star site mentions that it is most efficient if put in a hot area of the house (can we say attic?) because it puts out cooler air as a byproduct. (can we say stick it in the garage for a cooler garage??!!)