Reliable Reasonably Priced Window/Wall AC & Heat Units?

[Jon S.]

I purchased a duplex with broken window unit installed in wall of living room. Its a 26" Wide opening. The unit is a 2/1 with total 625 sf. It's Florida, where it gets very hot, doesn't get cold very often and doesn't get extremely cold, but it still needs both cooling and heat. Hpow many BTUs do I need to install? What AC/Heat brands and models have you been happy with? What models would work well for this purpose? 

Thank you