I have a standard pillowtop, no memory foam. I've slept on sleepnumber and memory foam. None are appreciably better. Mine I got for US$200 when the Sears outlet was going out of business. It's a California King. So I'm a cheapskate. I blame the Scot in me.
My sleep generally depends on how much energy I've expended. Best nights sleep are on the ground, in the sleepingbag, after the long hike up the mountain. If I don't sleep outdoors once a month I get barnsour and start biting the walls. Good thing I live in Southern Cal, otherwise I'd get cold, and wet.