About a year ago, my wife and I were wrestling with the same questions. By way of background, I will say that--prior to our first timeshare purchase--I was (and remain) a Marriott Gold Card member and have nearly 800,000 points in my account, thanks to many years of business travel with Marriott.
Here are the considerations we had on this topic, and our conclusion:
* Of the major hotel chains which also operate timeshares (Marriott, Starwood, Hyatt, and Hilton), Marriott has by far the largest network of TS properties. The properties are well-managed, clean, and offer plenty of luxury for a quality family vacation. Resale value is among the best in the industry, though I will also say that--if this is a primary consideration for you in choosing the right timeshare purchase, then consider not purchasing timeshares, as this is NOT an investment for which you can expect to achieve a positive return. Maintenance fees are, for the most part, pretty reasonable--and are lower than those for Hyatt and Starwood. Marriott trades internally on a weeks basis, so that you must trade your week for a week at another Marriott property if you want to trade internally. Overall, Marriott is a solid choice.
* Hilton is the second-largest hotel-based TS system. It operates on a points basis only. In fact, when you buy into the Hilton Grand Vacations Club, you're buying points--not a particular location. These points are fully transferable within the HGVC system for any of their locations. Hilton's quality is also very good. While this is strictly my own opinion, I would rank the quality of the properties among the four hotel-based chains as follows: 1) Starwood; 2) Hyatt; 3) Marriott; 4) Hilton. That said, the fall-off from 1-4 is not significant. I would be quite happy with any of these four chains. Hilton's MF's are comparable to Marriott. Hilton also has good comparative resale value.
* Starwood has the third-largest number of properties within their timeshare portfolio. Of all the hotel-based timeshare networks, Starwood's properties offer the most consistently high level of luxury and appointments IMHO. This is not to demean the other chains at all. Almost by definition, when you purchase in any of these networks you are buying a vacation experience which is among the finest available anywhere. But for overall luxury, I put Starwood at the top of the heap. One other advantage that Starwood has its uniquely flexible points or weeks program. In the Starwood system, you purchase a home resort week which equates to a certain number of StarOptions. These StarOptions are available for internal exchange--either on a week or daily basis. This means you aren't restricted to exchange for one full week at one resort. For example, you could conceivably trade your week at Westin Kierland Villas for three days at Westin Kaanapali and four days at Westin Princeville, for example. One big negative of Starwood is that the MF's tend to be among the highest in the industry. While that is true, I can also say that the high MF's do buy you a truly high-end location that is exceptionally well-maintained with highly-trained personnel and luxury service.
*Hyatt is the smallest of the four major chains. That said, the properties are of exceptional quality in very desirable locations. One interesting thing about Hyatt is that they have properties with little direct competition, including Carmel, CA; Lake Tahoe, CA; Sedona, AZ; and Key West, FL. Hyatt's structure is similar to Starwood in that you purchase a home resort, but your week carries with a prescribed number of points which are tradeable within the Hyatt system. It is very flexible. Hyatt's MF's are higher than Marriott or Hilton, and roughly equivalent to Starwood.
So, with all of this information, where did we choose to purchase? We went with Starwood. While we recognized that the MF's were high, we also decided to purchase at a place we love and visit often--Kauai. The only other major chain with properties on Kauai is Marriott, but we particularly love Princeville and the North Shore. So location was a key consideration. A second consideration was that we wanted to pamper ourselves when we go on vacation, and Starwood--to us at least--offers the ultimate pampering experience. Finally, we really liked the flexibility. The other properties within the Starwood network are in desirable locations for us, including properties in California where we live so that we can take some vacations at Starwood resorts within driving distance of our home.
I hope this helps. Please recognize that much of what I've offered here is strictly my own opinion and I am sure many other TUGgers would disagree with some of what I've said. I wish you the best in making the right choice for you and your family.