Direct From Disney: Disadvantages: high, non-negotiable, per point price although if you want a new resort like Poly, direct purchase is often the only way to go; may have to wait list for an older resort. Advantages: easy sale to closing process, financing if needed fairly easy to get (though loan rate is high), can make reservations right after sale rather than waiting until after closing, can get exactly number of points wanted for use year wanted, and points usually begin some months before purchase and thus you get a second allotment within less than year of purchase.
Resale: Advantages: Price per point is way less than Disney (except if buying new resort); price and who pays what proportion of closing costs are negotiable terms. Disadvantages: slower sale to closing process including because seller can easily delay things just by not returning paperwork quickly; cannot make a reservation until after closing and you are in system; financing if needed can be more diffiuclt to get and likely high interest rate unles you have own source of lending (e.g., home equity loan); may have difficulty finding contract with close to number of points and use year you want; quality of contracts differs and affects price (e.g.,. full contract may have all current points and some banked, stripped contract may have no current points and next year's are already borrowed and used; thus need to carefully evaluate the contracts being sold to know status of the points you are getting); Disney can take away your contract by exercising right of first refusal.
Some may also think a disadavntage is that a resale purchaser cannot trade out for certain of the Disney Collections (cruise, adventure trips, Disney hotels (other than
Disneyland), and collection hotels). I, like many, believe those are not a "benefit" having even a value 1% of the difference in price between Disney's price and resale. Those things are overpriced in point value, point price can and does go up annually, those who are buying now from Disney will likely need to buy more points in the future to even be able to use the collections in 10 years, and Disney can actually take away the collections from even those who purchase from Disney at any time it feels like it.
As to use year to purchase, the better use years are those that begin shortly before you usually go annually and the worst are ones that start just after you usually go. The reason has to do with being able to bank if you have to cancel and it has nothing to do with when you can go (always any time of year regardless of use year) and when you can call to reserve (always 11 months out at home resort and 7 for others.
In considering which resort to purchase, there are important factors to consider other than price per point, number of points needed for usual trip, and which resort you like the most: (a) length of contract: BWV, BCV, VWL, and much of OKW still owned by members, have a January 2042 end date (which means everything you own is gone when that date comes); SSR is 2054, AKV 2057, BLT 2060 (VGF and Poly even later as new resorts); (b) time of year you go: peak season for DVC at WDW is late Sep through marathon weekend in Jan and off-season is rest of year; if you want any near park resort during peak season you better own at the particular resort and use the 11 month window; if you only go between mid-Jan and mid-Sep, you can usually find rooms at two or more near park resorts at 7 months out even during the holidays in that period; (c) category of room you may want: studios are usually the first to fill and thus can sometimes be harder at 7 months out than others; certain room categories can disappear year round before 7 months out dictating that if you want one of them, you should own at the particular resort: AKV club level and value, BWV standard and boardwalk view, BLT standard view, VGF studios; (d) annual dues per resort: traditionally some resorts have always had annual dues higher than others and that is likely to continue in the future; for history of the annual dues per point per resort go to the DVC Resource Center, second post in the thread:
http://www.disboards.com/threads/dvc-resource-center.2823949/