They should carry each other. Gameplay without story means I probably won't remember it as magic and uhmayzing and I might not want to come back to it after a couple of play sessions. Story without good gameplay is just a plain bad game. SO gameplay is definitely more imoportant but they both count for a lot.
Some of the early final fantasies I stuck with purely because I did enjoy the story. (I'M LOOKING AT YOU, JOB CLASSES...)