Choice between an Origins Comfort 1000 or an Origins Pocket 1500

I am 51 and have chronic lower back pain and bursitis. I need a supportive but comfortable mattress at an affordable price. I sleep alone. I am 5'6 9 and a half stone. My base is beech sprung slats. Would the origins comfort 1000 be good for me on this base with my pain issues or would an Origins Pocket 1500 be better?