A
DVC-discounted regular WDW Annual Pass (Ages 10 and Over) -- which provides 366 consecutive days of admission to the 4 major theme parks only (and then expires) -- is $379 - $100 (discount) + 6.5% tax =
$297.14.
An advance purchase 6-day Park Hopper Plus (Ages 10 and Over) -- which provides 6 days at the 4 major theme parks and 3 days at the "plus" attractions, such as water parks, and which never expires -- is
$295 including tax.
Based on the numbers above, a DVC Annual Pass and a 6-day Park Hopper Plus cost just about the same. For 6 days, the 6-day Park Hopper Plus is without-a-doubt the better value because of the Plus features.
Beyond 6 days, it's a matter of how much you value the Plus features. I'd rather have 3 Plus features than 1 more theme park day, so even for 7 days, I still consider the 6-day Park Hopper Plus to be a better value.
For 8 or more days, the DVC-discounted Annual Pass looks good to me.
However, also consider that another advatange of the 6-day Park Hopper Plus is that the days don't expire. Let's suppose you think you'll go to the 4 major theme parks exactly 7 times in a 366-day period, based on nights that you've booked or that you plan to book. But what if, during your stay, someone is ill or you decide to go to Sea World. No problem. Your Park Hopper Plus passes will be good on a future visit. But with Annual Passes, you may have just "broken" your economic case for buying them.
By the way, an advance purchase 7-day Park Hopper Plus (Ages 10 and Over) -- which provides 7 days at the 4 major theme parks and 4 days at the "plus" attractions, such as water parks, and which never expires -- is
$317. That's worth considering too. For just $22 more than a 6-day Park Hopper Plus, you get an additional theme park day and an additional Plus feature (neither of which expire).