Rodney, I do both. But I also have pusher fans. So, I have the puller fan thermostatically controlled, but the manual override switch on the dash controls both the puller and pushers. It's a redundant set up, in case something fails on one it won't affect the other. All on circuit breakers that automatically reset. Being the anal nut that I am, I had to make a detailed post on it all.
Here it is:
Cool Modification - For Pusher Fans Only, Though