nipple sheild suggestions?

Diddle
Ok- this will be my second baby and with my first I had to give up Bf on my first one after a month because my sons latch just killed me, he would twist the nipple and take chunks out. I ended up pumping for several months so I was even more tired than I needed to be and didn't get to enjoy being with my baby. I have been looking into nipple shields----wish I would have known before but the laction people never returned calls or emails :(  
My question is which brand did you use and also how do you know what size??? Did you find one worked/felt better than than the other?
Thanks!!