I thought HGVC had a huge advantage with flexibility and being able to trade for a studio, one bedroom, or two bedroom and reserving for three days to three weeks or longer. Where Marriott is on a weekly basis. If this is still true, I would dump Marriott and go with HGVC just to get more flexibility.
It sort of depends. MVC came out with their own brand of points based reservations, and it has some advantages over HGVC and some disadvantages. One big advantage MVC has is the ability to make one night reservations using points. One disadvantage is when converting a deeded week into points, there's a "skim" where the points you receive for your week are not necessarily equal to the number of points it would take to reserve that same week. However, MVC's club membership covers all fee's where HGVC charges ala carte fee's to do anything other than use your home week.
Honestly they are both very different systems and can be difficult to compare. It just depends on what your individual needs might be.
MVC is considerably more expensive then HGVC as far as MF's are concerned.
MVC's points based exchange system has more flexibility than HGVC IMHO (MVC can book as little as 1 night, can book any resort 12 months out or, 13 months in advance if you own enough weeks/points)
HGVC's points reservations are a little more rigid, making it more "economical" (if you will) to book a reservation. MVC's points are very dynamic with regards to high points requirements for high demand dates (no real seasons) than HGVC.
HGVC's online system allows for easier searching for available weeks. MVC's system tends to be laborious to use IMHO when "shopping" for vacations.
MVC has a greater number of desirable locations, especially in Hawaii or the Caribbean.
MVC does NOT treat resale owners the same as developer purchased weeks when it comes to their points based exchange system. Resale buyers of weeks are essentially excluded from putting their weeks into the points system and resale points purchasers have some significant restrictions on usage. I would NEVER consider buying resale MVC points due to the restrictions on usage and, I would NEVER buy points directly from MVC because they have very little value on the resale market plus, they're WAY to expensive.
In short, we own HGVC for their availability in Las Vegas, Oahu and the Big Island. We really aren't as enthralled with Oahu anymore so that's become a non-starter for us. We have a reservation for the Big Island and we'll see how we feel about that in a couple of months. We really enjoy Elera and it has become our favorite timeshare location in Las Vegas, even though we own a 3 bedroom unit at MVC's Grand Chateau. We really enjoy MVC's variety of locations and absolutely love our home resort of Ocean Pointe, where we return every year. Our MVC Grand Chateau 3 bedroom ownership was originally purchased to use the 2 bedroom side and exchange the 1 bed room suite. Then HGVC went and acquired Elera and now the Grand Chateau either gets exchanged for MVC points or straight weeks exchanges, typically within the MVC system.
Personally I wouldn't get rid of either system. They both fill a need in our vacation lifestyle.