I have a foam box mattress, can’t remember which brand but it’s about 6y old and I find it comfortable. Have previously had sprung mattresses and I find the foam just as comfortable. (Disclaimer- I don’t have back issues so I didn’t have any specific needs). One thing to note, it was a bit smelly initially as the foam degassed, so maybe plan to set it up on a day you can leave the windows open all day so it can air out.