How much are you willing to pay?
We shop tested loads a few years back and in the end splurged on a Tempur Cloud mattress.
Cost about £1400 – it was in the sale, and we managed to get a couple of their memory foam pillows thrown in (normally £90 each!) along with the mattress and pillow protectors.
Expensive, but I’ve not slept so well in years. My wife was suffering really badly from lower back pain, and this seems to have sorted it out. I’m a night-time tosser(!) and turner, and she doesn’t moan about that anymore either.
If you figure it should last 8-10 years then £140ish pounds a year for sleeping like a baby is well worth it.
*edit* and Furniture Village did it for 0% finance with a 30% deposit. So the cost seemed a bit more bearable.