Worldmark (sold by trendwest) is one of the biggest and best point based TS companies in the US. With lots of TS in the western US. They are highly recommended here on TUG and buying them resale will save you >60% over the price trendwest is selling them for.
There are several other point based TS like Hilton Grand vacations, Club Intrawest, Shell Vacations, Monarch Grand, Bluegreen and others.
There are also several TS where there is a point based portion of the TS. Sunterra, Fairfield and Starwood (Westin & Sheraton) are an example of these kind of TS companies. These are more complicated and after buying you may have to pay extra to join the point based portion of the company.
The best advice you will get is two fold.
1. Buy resale!!
2. Educate yourself as much as you can before buying. It is easy to buy and hard to sell. So, read as much as you can before even thinking of buying.
Good Luck