We sleep on the fiber type (coconut fiber). At first you might feel it is hard but it really is good for the back. After we've got used to it it is a non issue now, we can sleep like a baby on it. It is quite cheap, we bought it at RM700+ 6 years ago (Dunlopilo), now maybe 1k+. Before using fiber we were using the box spring type but both felt back pain (ours might not be a high end model, around RM1500), after using fiber type no more pain. I really recommend fiber to people who wants to try mattresses that are not expensive yet provide good support.