Which racquet should i use??

since you have demoed them both, now it;s up to you to choose which one is really suitable to your swing style. if you play with more power then you should choose smaller headsize. otherwise if you have slow and compact swing you should get bigger headsize (preferably oversize) and remember to build your muscle with some weight lifting exercises (ask your coach or some local pro on how to do this exercise). once your muscles are built and you can generate more power on your own (you'll notice that you hit more ball out of bounds while using oversized racquet), then it's time to move to smaller headsize racquets. hope it helps :)