I'd have to say that Disneyland is my favorite, hands down. Maybe I am biased being a West Coast Disney Fan, but after going to both parks, Disneyland still stands out as being better.
It is the original park where Walt once walked. You can't enter under the railroad crossing without being transformed back in time to when you were a child. It is truly magical. It is the park where I first met my cartoon friends, spent my graduation night from high school, proposed to my wife, and have shared more laughs with my kids than I could ever possibly count. To me, there is no way that it can be topped.
Now don't get me wrong, I've been to FL as well and had a great time there. With so much to see and do, it is definitely a top vacation destination for my family. That being said, WDW as a total package might get more votes here because it has more parks to offer than the resorts in CA do, but if you were to judge purely by comparing DL to the Magic Kingdom, it would be no contest. Disneyland would top the list everyday and twice on Sunday....