I've been to both and I definitely prefer DL. I've lived in CA all my life, so I'm sure that influences my decision. I still remember my first visit (I was 4) and how excited I was to see Mickey and Minnie and go on the rides.
For me, DL feels much more intimate and magical than WDW. I loved it even when there was just one park. WDW is too big in my opinion. I was just there in July for 6 days and still feel like there was so much that we missed. And, even without the flight, it was so much more expensive because there is so much more to do. WDW was more overwhelming - where to eat, which park to go to, what rides are at what parks, etc. With DL/CA you just walk across the walkway to get to the other - no busses, no monorail, no boat, etc. You walk a few minutes and you're there. All the rides, shows, parades, etc are there in one place!
I like that I can drive to so cal and spend even just one day and still be able to see and do a lot. There is no way I could do that at WDW - and I tried it once.
Even though I loved my vacation to WDW, I just didn't feel that same magical feeling I get when seeing the castle at DL. I can see Walt's dream at DL and it feels perfect, and I don't get that same feeling at WDW - I get the feeling of "What more can we add? How many more hotels can we build? How much more money can we make?"
The other thing that I love about DL compared to WDW is the It's a Small World ride/entrance. At DL, it is huge and beautiful and such a landmark to me. At WDW, it's just a little sign outside a building - it was extremely disappointing the first time I saw it.
I've loved the three times I've been to WDW, but it still does not compare to
Disneyland in my opinion. I'm taking my bf to DL for his first visit in December and I can't wait!