Gel or sprung/gel combination

We would like a mattress for a sprung slat Base. We are 5,5 - 10.5 stone and 6,0 - 13st. We currently have a pocket sprung firm. We both find this too hard, we are side/front sleepers. We are trying to decide between gel which we like the top feel of or sprung with gel. We like the medium mattresses of both types when we try them.