whatever you use just remember that your baby will suck it off - and it's a tiny little being - so if you wouldn't eat a spoonful of whatever you plan to use don't put it on your nipples.
I have never used a nipple cream and i've breastfed 3 children. Nature wouldn't make a food delivery system that needed maintenance like that. If you have sore nipples the best thing to do is rub breast milk on them (also great if bub has a sticky eye) and then 'air' them and never use soap on your nipples.
I emplore you to read a book on breastfeeding before you have your baby - anything by Sheila Kitzinger is excellent. In our society we haven't grown up with breastfeeding being the only feeding method - in fact it is the exception - and it has allowed all sorts of myths and misconceptions into 'common knowledge' (like the 'need' for nipple cream). You need to read as much about breastfeeding as you do about pregnancy and birth - then you will trust your body.
I wish you a happy and healthy feeding experience - and remember - if your body can grow the baby it can feed the baby