Surf off which foot?

I’m gonna get me a new board, and noticed the talk about surfing off your front/back foot. I just surf, of course turning with my back foot… i’m an average joe surfing 5’11-6’3 most of the time, but how do I know what to tell the shaper, is’nt surfing a lot of the back foot the same as surfing vertical-a-la-kelly all the time?