The main problem with your idea is that you don't have any basic criteria, how can you compare a 5 CP symmetrical to a TC, a PL to a CP steel gametype, these don't have the same criteria about the work spent on it, neither the gameplay, optimisation, and even the detail. I'm sure if I create a TC, I will run out of brush and props and couldn't detail the map like a freak, while with a 5CP sym, I would have the opportunity to detail it how I want.
You know it would be frustrating for a guy who has created a TC to see that a 5CP sym, or even a 1 stage A/D, win the contest, just because it's more fun or the gameplay is "better", you know, if it's not equal, adjusting the gameplay on 6 stages and even actually create 6 stages wich are good, is waaayyyyyy more complicated than just creating one for a 1 stage A/D.
So please, just do a TC/CP_steel contest, and make it team up.