I'm sure it's buried in the forums somewhere, and the search either brought it up and I missed it, or didn't bring it up at all: Why Gallente ships? Catalyst, Thorax, Brutix, et. al. Why Hybrids? Has there been an analysis posted which I missed, comparing auto-cannons to blasters, hybrids to lasers?
The answer is very simple: blaster platforms are king when it comes to dishing out pure DPS, which is usually the only thing that the ganker cares about. A T2-fit Catalyst can be pimped up to 750 DPS with overheating and implants, which is unrivaled by any destroyer out there. The cost of 8-10 million ISK a piece arguably makes the Cat the most cost-efficient ganking ship, which is the entire point of asymmetric warfare. T1 fits are even more cost-efficient if you have the numbers.
Minmatar ships are a confident second. Instead of being stuck to the thermal/kinetic damage profiles, they enjoy a wide choice of ammunition, which is useful for ganking mission runners and other targets that require expoliting their resistance holes. Thrashers also have a better tank (valuable for ganking under gate sentries) and can fit microwarpdrives easily, which is critical for catching those mission runners. Tornados are famous for their awesome alpha, but their use has waned with the advent of ganking cruiser fits, so they're rarely seen outside trade hubs.
Other races' ships can sometimes be seen ganking, too, but lasers and missiles are simply not as good as the former two in terms of DPS, so they hold rather exotic niches.
If you are choosing the race for your ganking alt, don't bother yourself with thinking about the ships you'll be flying and just roll the kind of character you want to see. With Gallente, you'll need several hours less to fit your first Cat (in fact, it only takes 15 minutes for a fresh Gal toon to train up to the T1 fit) and will enjoy an additional bonus of Velator rookie ships that have a bonus to blasters. However, ganking with rookie ships is a rare occasion for when the fleet has overwhelming firepower and just wants to fool around. Other than that, different races have no penalties on training for different ships and fits whatsoever.