As a longtime DLR veteran planning our family's first trip to WDW, there are a lot of points raised in this thread that are interesting. The two words that I can best describe the differences between the two parks, for me right now, is Planning and Options.
I love to plan. And the gigantic nature of the WDW resort necessitates careful planning for us (both due to my unfamiliarity with WDW as well as the sheer size of the resort). Planning which park to go to on which day, planning dining reservations, planning FP+ for each day, planning shuttle times to/from our hotel, etc. Planning has allowed me to get familiar with the resort, attractions, and each park and what they have to offer. To me this is not a bad thing. On the flip side, DLR requires very litte planning (which isn't a bad thing either). I can't remember the last time we needed ADRs as we can go to almost any restaurant day of and get seating. Legacy FP obviously doesn't require 60 day advanced planning (but until I experience FP+ first hand I'll reserve commenting on this process). Proximity of everything within the DLR makes park hopping easy, quick, and allows for spur of the moment decisions on what to do and when to do it. Also, many have already commented on this but due to the ride concentration at DLR within DL and DCA, there aren't many rides that require pinpoint planning (save for RSR in DCA, or PP at DL). I'm a little nervous about ride wait times at WDW, especially on secondary rides as this is not a problem for us when we go to DLR.
As for options, WDW has this in spades. From hotel options (and range of pricing for resort hotels) to dining options and even Character options, WDW is just bigger and offers more. We like to stay onsite, and that's our preference so it's our choice to pay the rates of DLR hotels, but all three are equivalent to WDW Deluxe hotels in terms of pricing. I like the hotel options at WDW and the pricing tiers. As far as dining, there are so many restaurants we would like to try, it's somewhat overwhelming. It will be nice to try different things at WDW. That's not to say we're tired of the food at DLR, but I'm looking forward to the dining at WDW. As for Character options, WDW seems to have a lot more character meet and greets than DLR. We are character fans, and I like the wide range of different characters to meet and I like the organized meet and greets. There's like seven different Donalds at WDW!
Is one resort better than the other? No. They're different. For us, since we live out west, WDW is more of a vacation destination for us. A rare treat. DLR is also a treat, but it feels more like our home. Everyone loves their home, but everyone loves a vacation as well.