Just went to DL in late April. It was beautiful, lavish, and any other synonyms for pretty you could think of. But it wasn't WDW.
At DL I found myself feeling so much more confined and congested due to its smaller space and all the rides being packed together; I found it made it more arbitrary to rapidly get on a ride, get off a ride, and head to another before the crowds got unfriendly (yes, even during the off-season). At WDW, it feels much more spread out, making the lesser abundance of rides in WDW parks almost a good thing as you can get a better breath of fresh air and take in more signature Disney atmosphere no other theme parks can replicate (granted, I haven't seen WWoHP yet...).
WDW is so much bigger, with loads more things to do. The resorts at WDW are so much more abundant and thematic compared to the hotels of the DLR. Just compare a Birnbaum WDW guidebook to a Birnbaum DL guidebook, and you'll see what I mean.
The dining is unquestionably better at DW.
During my experience, I easily found the CMs a lot more shallow and cold than the ones at DW. That's not to say they weren't welcoming, they just lacked the general courtesy and cheeriness that makes the ones at WDW so...special.
For nostalgia reasons, WDWs monorail beats out DLs by a long shot. Don't take that seriously, anyone.
And frankly, I generally like the attractions a lot better in WDW than their DL counterparts. WDW Splash > DL Splash, WDW BTM> DL BTM, WDW ToT > DL ToT, WDW HM> DL HM, The Seas > Sub Voyage, Dinosaur> Indy (yes, crazy, I know). Not to mention all the awesome WDW originals like E:E, Epcot, Mickey's Philharmagic, the TTA, etc. Speaking of the TTA, I personally thought DL's Tomorrowland did not meet my expectations. The empty Peoplemover track and the lack of a cohesive theme made me wish I was in WDW's (Nemo in TL seems a lot worse to me than Stich and Monsters in TL).
And all the nostalgic value of WDW that biased my opinions.
DL is a nice place to visit, but WDW is a vacation kingdom. DL was Walt's original, but WDW is his pride and joy.
I tried and tried, but this I simply cannot understand.