I never finished either so its not like I'd rate either highly but XIII seemed worse in terms of both gameplay and story. Up to the point I reached XIII seemed like choice almost didn't matter in the gameplay. You cpuld do autobattle pr choose betweem two options and it almost amounted to the same thing either way. The most important thing seemed to be to act fast not so much what you did. Even of that applies to XV, and I honestly think it doesn't as much, at least going more fully action RPG made it more palatable. The plot of XV up to the point I reached wasn't super interesting but it was fine and pretty easy to follow. The plot of FFXIII up to where I reached seem to consist almost entirely of people repeating made up words without explanation.