When I first came across the NFL, I chose the Vikings and Ravens because they were in purple uniforms.
After having followed the league (very casually) for a year, I had gained sympathies with the Browns, the Chiefs and the Rams.
Now, after 11 years, I'm all Ravens - but still follow Browns and Rams -- and have picked up Lions, for some reason I don't even understand myself. :-)
It rules being from outside of NA, so there's no "Well you're from Minnesota, why aren't you a Vikings fan?" and such.
Also go Crimson Tide, because I like their red color and I've been to 'bama.