so i like to keep my options open for champs so i can fill whatever role is needed. however im having trouble deciding on a tank. i have narrowed my choices down to amumu and sion. so i have come here to see if you guys can help me choose. thanks.

neither of them play blitzcrank hes a tank and the best harraser in the game. you just stand there and watch people back off affraid that thier gonna get grabbed...... hes got self speed buff aoe ult and is a tank what more do you need..