Personally, I want my next one to be a Tempurpedic mattress (or something similar). We have a really hard mattress (our old one expired under the warranty, and they didn't make a pillow top in a similar model- should have complained, but, ah, we were young and uniformed
) and I have scoliosis, so it was too hard for my back and hips. I put 2 regular foam mattresses on it. Still not great, but better. Added a Memory foam mattress topper- much better! Added a second recently, and I was afraid my DH would complain that it was too soft. He gets in the bed that night and asks "Did you get a new mattress?'' and I think "Oh no, he hates it" but he thought it was great! LOL!
My suggestion would be to go to a few mattress stores, lay on each of the mattresses for a little while, and see which one you like the best (that's what they're out there for
). My favorite (when we thought we would have to get a new one) was a regular mattress with a memory foam pillow top- heaven!
Also check the warranty- worked out great for us, as ours pretty much fell apart after just a few years on a 10 yr. warranty. Good luck!