Neither one is really worse or better, what works best for your weekly routine is what will be the best. If you don't have 2 hours to do a full body, obviously splits will be better. If you can do a full body but have other activities that will tire you out that day, it might be better to do splits as well. Some days I do splits some days I do full bodies, depends on the full routine I have for the week. And yes I would suggest to take a rest day at least once a week if not twice if you're doing splits.