We are going to be closing on BWV soon, but we were within an inch of buying a Marriott 2 bedroom lockoff in one of 2 other places (Ocean Pointe or Aruba). Here's why we went with DVC instead:
1. We go to Disney on a reliable basis (at least every other year), and it is the only place we currently go to on a reliable basis.
2. DVC retains its value and Marriott (and many others) do not. This does, however depend on which Marriott property you buy (the ones we were going to buy seem to have high prices, but are still much cheaper on the resale market than from the developer).
3. We don't necessarily travel on a weekend-to-weekend basis: We may go away for long weekends, or we may go Thursday to Thursday, or we may go for 9 to 10 days. DVC has drawbacks for this (the points required on the weekend) but if you combine with cash you can work it out. It is a pain or impossible with Marriott.
4. On TUG, many people report that, if they own a floating week, they often have difficulty even getting through to Marriott on the day they need to book their week. Therefore lots of people with kids etc report they have difficulty using it on the week of the kids' vacations.
5. When we have gone to Disney the last few times, we have found ourselves staying at the Boardwalk villas either by renting points or discounted cash reservations.
6. In the end, there is not a huge difference between the fees you pay at DVC vs. the annual fees Marriott was charging.
7. Our vacation times are going to vary depending on our work and kids' schedules so we need lots of flexibility.
So that's why we went with DVC. On the upside, a good solid Marriott or other TS will allow you to trade to some great places. However, these don't necessarily guarantee you the week you want or need.