Loving this thread. I am a DL native. I've been going to this park my entire life, I know every corner and every ride. My husband and I just honeymooned in WDW this past October. It was very interesting. Being a Disney nut, everyone asked me when I got back "so, which is better?" I couldn't answer. I can go park by park. Epcot and AK are unlike anything we have in California, so they can not be judged. I LOVE Epcot, and could spend days and days there. AK is amazing as well, I could ride the safari everyday. I CAN compare HS to DCA. I liked HS better, maybe because Rockin Roller Coaster is one of the best rides i"ve been on in recent memory, maybe because ToT is so much better...maybe because of Star Wars and that theme...but HS does NOT have WoC, which is my new favorite Disney show ever, nor does it have Aladdin, which is so fabulous (but AK has Nemo, which IMHO was right up there).
Now to the big one. DL vs MK. Walt vs Roy. Here is what I think, I think in Florida they had SO much more room to work with, they were able to theme it so much better. I think that is what the OP meant by atmosphere. When walking through the queue at Pirates, it is a completely different experience than walking the queue in DL. Everything is so much more adequately themed, because they had the room to do it. And because the park is so much more spread out, the crowds seem so much less. A crowded day at WDW seemed like a very quiet day at DL. As far as rides go, I think DL takes it on that, though Haunted Mansion in WDW is awesome, with the extra room that we don't get here. Though I like our mansion better, though that may be nostalgia talking, and I like the fact that the stretching room is the elevator, not just a room that stretches. The castle at WDW, amazing, huge, monstrous. Our castle is much smaller, but again, has a charm (which may be nostalgia again).
End of story, I love my parks. I love that they are locals parks, that they are convenient, I can walk from IASW to California Screaming in 30 minutes, which is not possible in WDW. But I love the hotels at WDW, I love the dining options (something seriously lacking in DL), I love that once you are on vacation, you are immersed in the experience until you leave property and head to the airport, that every person you encounter is a Disney CM, and therefore every encounter has the Disney touch.
I think DL will always be my #1, and I think that it is the better park to be closer to, but I also LOVED my WDW experience, and think it is the better park to vacation at. If I have 2 days, give my DL, if I have 2 weeks, give me WDW.