I asked the same question here just a few weeks back...and we ended up buying a latex mattress. We've only had it just over a week so it's early days but so far we love it. The first morning I got up without the usual back pain that I've had for the last few years..yay! I still have some stiffness but it's greatly improved to what it was. Our's is classed as a medium and there's no pillow top on it and we like it just like that. We have to turn it for even wear and we were told to also make sure we use the middle of the bed at times...like if you got to bed and read :)
Good luck with your mattress hunting..there's just too many choices out there..lol.