i would say medium because the body will hold more, large rollers make your hair more weak and it will just end up flat ... if you want your hair more flat then use the big rollers. if you are going to go curly then go curly
why not both? if you use them the right way, the effect will be perfect :)
That depends on whether you want large or medium curls.
pfft go big or go home
just use them both