Advice on replacement memory foam mattress

Had memory foam for last 9 years. I'm 5.3 and 8.5 stone, husband 5.9 and 15 stone. I have multiple joint pain and too firm/hard mattress bruises my hips. Very hot with memory foam and recently roll together problem (mainly side sleepers) maybe because mattress is old, but very comfortable. What's the difference between hybrid and latex and which do you suggest for us please?