The Cooper handles better (less weight, better weight distribution) and it has better throttle response with higher compression ratio. It's more fun around the twisties than the Cooper S
The Cooper S is quicker but that's not really the point. If I just want straight line speed why not just get a WRX/XR6 Turbo then get a big boost. Not to mention the Cooper is actually quicker off the mark 0-30km/h ;p