After bad luck with a well known brand pillow top ( replacement was even worse) we bought a sleep number bed. DD has owned 2 of them for 12 yrs & never a problem. I already had a King size mattress topper,so put that on the new K size Sleep number bed 7 yrs ago.
Was always a restless sleeper before,lucky to sleep a few hrs at a time. it seemed strange ,sleeping till 7 am...smile.
We both sleep great,but ppl are different.Good luck with what ever you decide.