I'm another who agrees with using the steroid cream to get rid of it. It was the only thing that worked for us and moisturizing creams are good just to keep the skin soft and protected. As pp said try to find out the trigger. For mine its dairy, tomato and washing powders. I avoid the foods and use omo sensitive.
As for which cream, I found everyone had a different recommendation. Again try them and work out what suits your child best. For us it was Dermeze. QV was recommended by our paed but it was useless for us!