For car camping we now use 2 single flock mattrasses (millets, the range ext) which to me are very comfy. We do have a selection of (cheap) self-inflatable mats but I only find the army issue comfy-ish. Reading the previous posts has been interesting and will problably result in spending more money .
Years ago we spend several months in southern Africa and used those foamy things...horrid! 15 years and 3 kids later, no way!