I want to buy a snowboard and want to know what size should I get. I am 6.1"
I am tired of paying 40+ bucks for the rental...

Or is it my personal preference?

Thanks :)

Mostly preference... to an extent. In the adult range, the shorter ones are better for tricks, jumps, slaloming, etc, and the longer ones will be better for speed.

I always rent the longest one I can find: I like to fly! :p

(I'm an old man, the moguls kill my back! :o )