Looking for a replacement to our OME mattress

[ras100]

We have a 27-foot 2011 Sprinter with a short queen mattress. The mattress has built-in springs so it's like a combo. I'm sure many people have the same set-up. We have plywood under the mattress. It's really not that uncomfortable but I think we can do better. I would like to get a replacement but have looked at various options at places like camping world and haven't been impressed. Specifically, are people happy with just a mattress without the springs set on plywood? Thanks for any ideas or suggestions. BTW I did do a search and didn't get that much useful info.