In order from best to worst (my preference).
Light - Fire Moth, Kit Fox, Mist Lynx, Adder
Medium - Stormcrow, Nova, Viper, Ice Ferret
Heavy - Mad Dog, Hellbringer, Summoner, Timber Wolf
Assault - Executioner, Warhawk, Dire Wolf, Gargoyle
I use lights and mediums the most, being Clan Burrock. Specifically the Nova, Stormcrow, Kit Fox, Mist Lynx, and Fire Moth. When I need heavy firepower, I got with the Mad Dog, Hellbringer, Warhawk, and Executioner.