I try to pick a wide variety of models... stock ("Big Scale Beauty" Corvette from last issue), hot rods, customs, competition, etc. My intent is to mix it up as much as I can, and give as many different kinds of subject matter a spot on the cover as possible.
If you look back at the previous year or two's worth of covers, you'll find that there are a wide variety of models that made the cover... and that was not an accident.
A secondary issue is... what exactly do I have on hand at any given time? We can only feature what gets submitted, and sometimes I'll have a lot of things in one or two categories and none in others. Personally I would like to put a classic on the cover, but aside from Ismael Gonzalez' '33 Chrysler Indy Pace Car from quite a while ago, I haven't gotten anything in that category.