Lol, I chose most of them from video game ratings. I like the Atlanta Braves because they had good pitching in VR Baseball 99, the St Louis Rams because they had good offense in Madden 2002, and the New Jersey Devils because they showed up on team select first and had good stats in NHL 2001. Basketball was kinda hard since I only had Space Jam for a while, but I guess I would go for the Phoenix Suns now from having NBA Live 2008.
Although if it was college football I would go for Oregon since I have an aunt that lives there who used to send me Ducks t-shirts.