I voted puffer just because I keep them. Once I get a bigger tank I'm planning on getting some BGK's and I've playing with the idea of getting some eels for the tank I'm working on setting up right now.
I too voted puffers. But you forgot one oddball...Elephant Nose. These fish are amazing. I don't have one...YET...but everytime I go to a lfs that has them Im in awe. Yes, they are sensitive, but cool looking fish non the less.
Sadly puffers aren't available in the big ol' land of Oz I'd love a couple of dwarf freshwater ones. As the proud owner of two eels, both of which are my favourite aquatic pets out of all the ones on my list below, I defanantly voted eels. Gotta lurve that funky jive they do round the tank
Of the choices i would have to say puffers but there are so many oddball choices you have missed. Arowana's would be my favourite though bichirs gars snakeheads and gobies would also be high on the list.
On that list Eels but others would include, Arowanas, Birchirs, Gars, Snakeheads, Gobies, Heteropneustes Fossilis, Panchaxes, African Butterfly Fish and South American Leaf Fish.........
You left out arowanas, snakeheads, LUNGFISH , rays, bichirs....just to name a few....but i would have to say knifefish outa those guys...just too kewl!