I lived in California for most of my life and moved to Connecticut in the early 90s. I must say that I've been to Disneyland about 50 times. I've been to WDW and handful of times for the past few years. WDW has a significantly larger amount of stuff to do, but it is really hard to compare it to Disneyland, since the size of the two parks is so different.
I think it would be more fair to compare Disneyland to Magic Kingdom -- those two parks are really one in the same. If that were the comparison -- I'd say that Disneyland will win hands down. I feel the theming is much better in Disneyland than Magic Kingdom. However, could you make a several day or week long trip out of it, even with California Adventure? Nope. Disneyland could easily be seen in a day, two days tops. California Adventure can be seen in 1/2 day, 1 day tops (there isn't much to do at CA but there are a couple "must ride" rides like Soarin' and the roller coaster).
If I were to go to Disneyland, I'd also go and visit Universal, San Diego (for the Zoo and Sea World), Knotts and a few of the other local attractions. All are within driving distance of the parks (San Diego is about 1.5 hours away, Universal about an hour and Knotts just down the street). When visiting Disneyland, you have to think outside the Disney resort to find entertainment to fill and entire week or more.
If you don't want to leave the Disney resort complex, I'd say go to WDW. There is MUCH more to do and you can easily fill 1-2 weeks of time. We go to WDW every year for 1-2 weeks and never run out of things to do -- and we have yet to venture outside of WDW. We usually visit DL when we go to CA for the holidays to visit the family.
If you stop by our website, we do have TONS of pix from both parks.