Simmons BeautyRest World Class Pillow Top. Love it. Hate the fact I had to replace all my sheets due to thickness. But over the last 3 years I have gotten over it. No more aches and pains in the lower back. I don't roll to the middle anymore, either. LOL!
Best advise is go try each of them out at the stores. Lay on them back side, side, belly down, etc. They will all seems better than what you have now. Me I like the mattres/box set better than the foam.
We had a memory foam and I hated it. We have a couple of sets from Sam's club right now and I really like them. It would be interested to see how long they last. I have always wondered if the Sleep Number had repair issues after a few years.