Favored use year is one that starts shortly before you usually go. Worst use year is one that ends within three to four months of when you usually go. What use year you have is irrelevant to when you can go (any time of year) or when you can call to reserve (always 11 months out at home resort, 7 at others). Its importance has to do with what happens if you have to cancel a reservation and its impact on banking points. Since points must be banked before end of eighth month of use year to be usable in the next use year, that is why having a use year that ends shortly after your usual travel time is not a good use year and one that begins shortly before your usual travel time is when considering the issue of possibly having to cancel and then being able to bank points that were in the reservation.
Thus, your ideal use year would be August if intent is to go in August or Dec. June would be second choice and even April would be OK (there are no July or May use years).
There is no
DVC resort that looks like Port Orleans and I cannot think of what would even be similar.
The typical Port Orleans room is 315 sq ft. Most DVC studios are in the 360 range. OKW and VGF are larger than that, BLT is about 340, and the value class studios (only a small number of rooms) at AKV are in that 315 range. The biggest differences you will find, other than size are: (a) studios have a queen bed and a pull out couch (double in most, queen in VGF) rather than two beds, except for OKW which has two queens; (b) you get a mini kitchen with a microwave, coffee maker, and small refrig, and (c) you don't get daily housekeeping service (fourth day they empty trash, change towels, and replenish toiletries).
You mention going August and Dec as off-seasons. Be aware off-season for DVC demand and Disney demand are very different things. Aug is a low to mederate DVC demand time but the time from end of Sep through marathon weekend in Jan is by far DVC's highest demand quarter of the year and Dec is the highest demand month with first week of Dec being the highest demand week and second week of Dec being the third highest.
As to whether DVC is something to choose, the answer is probably yes if you have the ability to pay cash for a resale, go every year, and want to move up to more deluxe resorts. Nevertheless, from a financial aspect, the answer may be closer to no or 50/50 if you are perfectly happy with a moderate resort and don't want to move up. With DVC you have the initial price that gets the room every year. You also have annual dues that can and usually do rise a little every year, Dues cover the costs of the operations and repairs of the resort, property taxes, insurance, etc and are generally set at a rate equalling costs but costs increase annually (labor is the highest cost factor overall covered by dues and people do get raises now and then). In the long run the combination of the price of points and dues paid over the years is likely going to be comparable to or even somewhat more than what you would pay every year for Port Orleans. Where the finances favor DVC is usually if your intent is to otherwise stay at deluxe resorts every year.