it's more about opinion, but it is known that chest zip is more flexible. I personally like the back zip since its a whole lot easier to get on and off, and i don't really notice a difference between the two flexibility wise. I have a 2mm short sleeve cypher quiksilver fullsuit thats a chest zip (got for $115 by the way 50% off on jackssurfboards.com) and it's a b**** to get on and off whereas it would be easy as anything to get on and off if it was a backzip. its all about prefence
