The classic, the original... Disneyland USA takes my top spot for favourite Disney theme park. It's not the biggest (Magic Kingdom), and not necessarily the most advanced (Tokyo Disneysea) or the best laid out or most attractive (Disneyland Paris), but it is the Disneyland. This is the park that Walt built, that he walked in, that is rooted in legend and engrained in that period in the mid-Fifties when the Disney company rose to its post-war heights. This is the park that all other Disneylands and Magic Kingdoms are a version of.
I've made the case before that Disneyland should be a museum, which was to say that you cannot separate what makes Disneyland great from what makes it historically important. It is the first custom-built theme park as well as Disney's first theme park. It made innovations like tubular steel roller coasters and audio-animatronics and a daily operating monorail. It is a place of artistic and engineering excellence merged together and dedicated to the noble goal of being "a source of joy and inspiration to all the world." Disneyland is an integral part of America's mid-20th century milieu, a product of that same glorious era for the company that produced some of Disney's greatest animated films like Cinderella, Peter Pan, Alice in Wonderland, and Lady and the Tramp, and Disney's first live-action films like Treasure Island and 20,000 Leagues Under the Sea, and when the company almost single-handedly sold televisions to every family in America with the Walt Disney's Disneyland television series, The Mickey Mouse Club, and Zorro, and when they invented the modern documentary with the True-Life Adventures and People and Places series. Disneyland even played its part to convince Americans to go to the moon!
Disneyland is entitled to some sentimentality and nostalgia. Would that it were as good as preserving its history as it is at milking that sentiment! Nevertheless, while I may have a list of grievances at things demolished and replaced with substandard attractions, or simply not replaced at all, or growing encrustations of things that are not Disney in Disneyland, there is still an indelible charm to the original Disneyland. Its modest scale compared to other similar parks almost gives it the feel of a delightful, whimsical dollhouse. It is every childhood daydream come to life, from cowboys and jungles to princesses and space ships.