Need advice on cushion

First of, let's get this out of the way. No, I will not get Purple. I tried it. Was a waste if money for me.

Okay, now that is out of the way.. I am a 110lb man due to illness. I need a cushion that will not be too hard on the back end. Firm/soft is where I'm at. I do sit for long periods of time so there's that (which causes pain on the cheeks and my back all the way to my shoulders and neck). I would appreciate any input, better if you are around the same weight as me and have a cushion that worked for you but otherwise any advice would be appreciated.

Edited to include the pain part I guess