NFL and it's not close. The NFL is comprised of the best of the best that college has to offer. NFL players are the best on the planet. In NFL games you rarely have to make a 4th and 2 decision based on whether or not your kicker can be counted on to make a 34 yarder.
If you want to see the best play week after week then it has to be NFL. I don't even know how big time college fans can go to some of the games. Let's use Bama as an example. Sure, they are the best college has to offer right now and SEC football is great, but is it really any fun to go to a game and watch them beat Western Carolina 49-0? Is there any doubt heading to that game what the outcome is going to be?
Sure, there are blowouts in the NFL too, but on any given Sunday any team CAN win. Did anyone think Western Carolina was gonna win that game, or when they played Western Kentucky or Florida Atlantic?
Boring.