Which mattress do you recommend?

I am 5' 8"and 14 st my partner is 5' 4" and 12 st.I am looking for a mattress to go on a platform base ( not sprung ).I have tried a number of mattresses in the past few years including latex, memory foam and springs with memory foam but have yet to find a comfortable one.They all have seemed to be too hard and made me fell like I was sleeping in the road!I have ended up using a memory foam mattress topper on them all - just to make them bareable.I have generally leaned towards a firmer feeling mattress because I do have some neck and back pain.Having read some of your articles on springs and upholstery I suspect I should be looking for medium pocket springs with a soft upholstery.Do you think this sounds suitable and which mattresses do you recommend for me?My partner has found all the mattresses we have tried to be comfortable and sleeps soundly with no aches or pains - unless I disturb him with my constant tossing and turning.Thanks so much.