You can get several kinds at Garden Exchange & Home Depot, and often 1 or 2 kinds at Walmart. I guess it depends on what kinds you like best really. The easiest is the dwarf Apple and it is many people's favorite. You can also go to the Makuu Market on Sundays, near Pahoa. At the north end there are 2 vendors who each grow and sell about 30 varieties but have maybe 5-10 types on a give day. My recommendations are Dwarf Apple, Dwarf Namwah, Mysore, and Gros Michel. There are many other good ones but these are my favorites that aren't particularly disease prone here, except for Gros Michel. If you like regular store bananas, both Williams and Dwarf Cavendish are good choices too. The vendor Marvin can tell you quite a bit about the different types he sells. I sell some too, but don't have much at the moment. My site is here:
Banana Varieties sold by Seaview Farms