Hey there,
Thanks OP for posting. This really is a great list. We have done both and we like both on and off site lodging. For us, it really comes down to price. If we factor in the rental car and compare the prices, generally off site comes out on top...especially because we are a family of five. While we LOVE the convienience of staying on site (and the Disney magic), the expense is generally just too much. A few years ago we got a super deal at the Villas at WL and it was awesome!! But, now we have a new baby and we'd probably need the 2-bedroom and on-site would be very expensive. If the hubby and I get our own trip (one day) or we decide to do a quick getaway with just one of the kids for a special celebration, we'd probably go for on-site. But, with the entire family, I say off site is the better match for our vacation dollars. But, both are fantastic as Disney IS the happiest place on earth!!
Happy planning pals!