For us going to WDW is a bigger expense. We can drive to DL, but we have to fly to WDW. I really wanted to go to WDW for our 10th anniversary in a few years (spent our Honeymoon there), but I've decided we're not going to. It's too expensive for us to assume we'll take the kids twice. And if I can only guarantee one trip, then I've decided I want them to be older.
Comparison wise: DL is not to be missed. WDW is massive, and it is a great vacation destination. You can hop on a bus from the airport and spend a week or 2 at WDW and never need to leave. DL is intimate. As others said, you can hop so easily from one park to the other if you want. It's a short walk from one gate to the other, and DTD is right there too.
Although people worry about the bubble, another way to save money is to stay across the street. It's often closer than the DL hotels, and a lot cheaper. You can also save money on food as there are plenty of restaurants within walking distance including the cheap McD's and Denny's & IHOP, at least one of which offers free kids' meals.
Also, less walking. The parks are smaller, but still crammed with rides. This means a lot less walking to get from one ride to the other. And many of the rides at DL are superior to their WDW counterparts. Small World and Pirates both come to mind. The Matterhorn is old and bumpy, but an experience you can't get at WDW (don't compare it to Everest though). Screamin' is a great coaster too. And Indiana Jones is a popular and thrilling ride, much better than Dinosaur. Someone mentioned Test Track as being a great WDW experience you can't get at DL, but Radiator Springs Racers uses the same track system and has better theming and storyline in my opinion. And with more rides, and better FP, the lines are shorter. At Hollywood Studios you could wait 90 minutes for Toy Story (although you could get a FP), and DCA the wait is 40-50 minutes most of the day, but short in the first hour.