I agree - We just got back (May 21-25) from DL, and usually go to WDW about 3-4 times/year......DL is just SOOOO much more crowded than WDW MK....... The walkways are smaller (the entire park is smaller), and IMHO - they just don't do as good a job at crowd control.....plus, IMHO - there are alot more rude visitors at DL than at WDW MK - (maybe I've just been lucky in the past, or unlucky this trip---but I have never encountered so many line-jumpers (not one, not two - but many parties and entire families jumping over the ropes - and NoOne (incl. CMs) said anything to them ----and at the fireworks - prepare to be elbowed and have your feet stepped on (alot) if you want to try to watch the fireworks from the Hub (The Fireworks are incredible, BTW - 17+ minutes long - but really designed to be viewed from the hub).
California Adventure isn't nearly as bad, size-wise and crowd wise.......