Go with the ATF! Don't know the difference between GATF and VATF, but if the GATF is anything like my VATF- there is no question. It is an extremely active fish that swims constantly in the mid to upper level of the tank. It is also a very well aware fish and times will interact with me (i.e following me, and when hungry attacking the glass). Also he is a voracious eater-feeders, red meat lasts no more than 2 seconds. Very fun fish.