I have a VATF, scomb and hoplias mala but my favorite has to be my Golden Dorado. My tiger fish is great athlete, but in open water my Dorado is unbelievably quick and nimble.Have to give a nod to the red wolf fish, the best personality of any fish I've kept besides cichlids.
There are a lot of cool ones, surprised that piranhas arent mentioned in this poll.
African tigerfish and vampire tetras are so similar, but both would be cool to have. I think I would prefer the vampire tetra just because they do not get crazy big.