E-Z Bar , this is OK if you feel your wrists are a bit sore from the straight bar. The reason I recommend the barbell/ez is becuase they allow you to 'cheat' a bit. Good form is essential on 95% of your sets but there are exercises, and BB curls are one of them, that allow you to cheat and swing a heavier weight than you could if you held strict form. This is OK as long as you don't go mad and can help squeeze out a bit more growth.