I do love betta fish, they are probably my favorite fresh-water species of fish.
However when it goes to my ultimate favorite, sorry, I have to say my heart belongs to the
Batrachoididae family, especially
opsanus tau and
opsanus beta.
That'd be an oyster toadfish for the curious. It's a face only a mother could love, and alas, I daresay I was a doting oyster toadfish parent for many years.

Besides, what other fish can you carry on a conversation with and actually have them talk back? Bettas aren't really very talkative fish, I must say.