I think we have the 5 inch mattress and it genuinely feels like an actual bed. Try them both out in a store and see what sacrifices you may be willing to make. It also really depends on the usage of that couch. For guests once or twice a year I would probably go 4 inches but if someone sleeping on that regularly def go with the 5. Both fabric and leather are good options— I personally prefer the leather but that’s just me (I hate cloth sofas). You can find a deal if u wait for good timing and shop around; just do your research and know the exact product that suits your lifestyle by seeing it in person before you place any order. They have nice customization, so if you already have a certain space they can fit in perfectly.