Mattress advice for two different weight sleepers

Hi John & Ryan. Please can you advise a suitable mattress for our situation from your range. I am 18 st, 6 foot tall side sleeper and my wife is 13st, 5' 3" front sleeper. We have tried several types in four years and no luck. This included a sealy Brisbane that ended up being too hard for us both and the topper failed, then a British bed company 1200 springs/" title="pocket spring">pocket spring from mattress man that initially was comfortable but sunk badly within a year. I understand from your site we may need a zip and link set but I am open to any suggestions.
Thanks