The fighting fish (Betta) gets that name from the fact that two males will try to kill each other. In some places, they actually stage fights with male Bettas and bet on the outcome, much like they do on dog fighting and rooster fighting. Personally, I find that sort of thing cruel and highly disgusting.
But back to your question. Male bettas are mostly dangerous to each other, but they are still pretty grumpy and will eat the fry of other fish. Since they can also breathe air like gouramis, they sort of occupy the same territory and could get a little aggressive. You might try a Betta, but have one of those desk top aquariums (two gallons or more) waiting just in case. If you want to see some really spectacular Bettas, log on to aquabid.com. It's also a good place to buy live plants that you don't usually find in local stores.
I once had a Betta in a 55 gallon aquarium, and his fins tended to look a little ragged because of all the swimming room. If your aquarium has lots of floating plants like hornwort and some low light rooted plants like java fern and Anubis Nana along with Malaysian driftwood, the fish will have plenty of hiding places. That cuts down on potential conflicts, and you can plant an aquarium before it's cycled. In fact, live plants will speed the cycling process, as will a product called Eco Complete. It contains live bacteria.
Before adding fish, make sure the aquarium has completely cycled. Please keep us posted on your progress.
PS: I never learned all the Latin names for fish and plants, so I probably got most of them semi wrong.