My TT mattress was the typical cheap piece of junk they all seem to put in. Was FT for many months and tired of a crummy sleep on it. I replaced the mattress with something decent and slept better but certainly nothing to write home to mother about.
So I went to Ikea and bought their deluxe topper and put it in. It actually helped. My body is permanently damaged, lower back, shoulders and more after being hit by a truck and a drunk driver so I need all the help I can get. The Ikea topper was a good choice. It helped more than the mattress did.
I would buy another one if the need came up.