I stayed at most of the Marriotts around Orlando, and they are by far better resorts than DVC. However, just because they are awesome resorts doesn't mean they hold as much value as DVC. Personally, except for staying on-site, getting DVC transportation, FP benefits, etc... I wouldn't have owed DVC, and would just continue staying off-site at the Marriotts, as I enjoy the Marriotts more. However, I see the benefits of 60 days FPs to make trips to the parks more enjoyable, so I suck it up and pay the Disney / DVC premium. But if I am doing any off-parks Disney trips, such as Universal or just relax time at the resort, I book outside of DVC, much cheaper and much nicer.
Having said that, I would not / never buy a Marriott timeshare in Orlando, those are the easiest to trade into for cheap, using a cheap timeshare trader. I own a trader with II and a trader with RCI that doesn't cost much to acquire, trades well, and I feel are fairly easy to give away when the time comes to exit out.
But yeah, research, research, research, which I know you will haven't seen what you done for a DVC purchase. Tugbbs is the best place to learn all things timeshare other than the DVC system.
Edit: As for other points based system, I also own HGVC and Worldmark. I feel those two timeshare systems as well as Wyndham offer the best values. Just don't attend any of their presentations, don't fall for the incentives, don't buy direct, only buy resale, and you will be fine. The only system where buying direct "might" make sense is DVC.
Great3