so wait do you mean favorite type of fish or favorite in your setups?
favorite in my setups has to be the beast my 12" oscar he's patiently awaiting an upgrade (finances wont permit it at this time, maybe fall after I get the refunds from student loans, going back to school for a masters to help fund my habits/hobbies lol) but is a veratious feeder and always greets me when I get home.
my favorite type of fish has to be the dragon moray eel but it's quite a bit out of my class to own. (financial and experience)