...Once we know locations then that will drive the result.
Indeed. As with all real estate what matters in a TS system is location, location, and location. That said...
Of the TS systems I own, HGVC is the nicest. You don't have to call at 9:00AM sharp to get your home week reservation. In a number of locations - e.g. Big Island, Las Vegas, Orlando - you don't even have to worry that much about Club Season. The MFs are reasonable for platinum weeks. And when you buy or sell HGVC the points come with the week.
That said, I own more of MVC because of Kauai and Maui. But the way MVC overlaid their points system over their previously existing weeks system means you need to learn a *lot* about the realities of MVC before you buy. And it's a pain to use. But given those strictures I love the locations and we have very much enjoyed our stays in SF, Boston, Wash DC, SoCal, and other places in addition to where we own weeks.
And then there's DVC. If it's worth it to you to stay 'on property' at WDW (it is to us...and the value of doing so seems to be ever increasing) then DVC is your choice. As with HGVC there is a Home Resort booking window...but since there aren't any weeks* you don't have to book 'your' week in that window. However, while DVC was once the best TS system in terms of resale owners they have since turned to the dark side. I was going to buy direct at Riviera...but the resale restrictions (actually the Membership and Resort Agreements for all owners) at Riviera are horrendous.
*There are a few DVC week contracts in the newer resorts....but very few. To buy them you basically need to have arranged with your salesrep to buy them the moment they go on sale (at least for popular weeks like December and Marathon week) and all of them sell in short order. I've *never* seen one for resale...though have heard tale of them occasionally appearing.