We all have different body dimensions so there's definitely not a single solution that works for everyone. My optimal setup is some of those interlocking foam exercise mats, with a thin mattress on top of it. One important thing is to flip the mattress and let it air out once a week or so. Sweat and moisture can't evaporate from underneath like it would with a traditional setup.

I tried a hammock a few years ago but wound up with worse sleeping posture because of the way my back curled. But I also have a friend who loves hammock sleeping.