I'm a vet in both parks. I grew up going to DL and started going to WDW as an adult when my children were young. I like them both, and still visit both.
I think it really is apples to oranges even though they are both Disney and imitate each other in ways.
As others have said, DL is on a much smaller scale...all the way around! This makes it easier to hop between DCA and DL, or get in and out of the parks, but at crowded times the smaller park with narrow pathways can really jam up. When WDW is closed for capacity it is crowded and has horrible wait times. When DL closes for capacity it is difficult to move. Anywhere. Unless the crowd simply sweeps you along in a mindless direction without control.
DL has many local visitors (a locals parks as some said). When "locals" go to WDW they generally still employ strategies to maximize their passes and time such as rope drop and avoiding already crowded days. When locals go to DL, it isn't uncommon for someone to say "HEY, let's go tomorrow". Forget about rope drop. You can see groups of kids arriving after school when the parks are open late. I have friends that like to go after their Thanksgiving meal. They consider it a good day to do space mountain, Indiana Jones and maybe Pirates, then watch some fireworks and call it a day.
DL has no room to expand and basically, it is now what it will continue to be. The 3 "on property" hotels are brutally expensive much of the time, and offer few perks compared to WDW resorts. Many many small/independent hotels are actually closer to the main gate. Even THOSE are pretty expensive for what you get, and some have a reputation for being downright filthy but still book to capacity frequently.
The rides are cool, even the old ones, sometimes just because they ARE the old ones.
I like WDW but often find it a bit overwhelming. The Disney "bubble" thing people talk about here doesn't actually do much for me. This is probably BECAUSE I grew up going to Disneyland. Seriously, we never ever went to Disney for more than 1 day in a row. Sometimes we would stay a night at the old Disneyland Hotel because you could take the monorail from the hotel to the park, and it was easy that way with young kids.
Sometimes I feel a little claustrophobic at WDW and 4 days in the parks is just fine with me. 5 days is a long trip, and I am ready to leave it all behind on day 6.
I don't think either one is "better". I think of WDW as "taking a trip", but we just "go" to DL. Hard to explain.
And I will say some Disneyland/DCA attractions are much better than WDW's (Indiana Jones, Space Mountain, Small World, Radiator Springs Racers, Matterhorn, Alice In Wonderland), but WDW has EPCOT and Animal Kingdom 
It's a give and take, but I am definitely grateful for both Disneyland & WDW 
let's just say despite having been to wdw 6 times as much than to DL ...you can tell what park is this kids favorite.
