I am going to be able to do a first hand comparison in a couple of weeks.
Hogsmeade blew disney out of the imagineering water a few years ago, in my opinion.. Diagon Alley will leave me no doubt of this fact, I am sure.
If you have the time and inclination, compare some of the you tube videos out there, the recent ones from the designers of DA at Universal, and compare it to the suits talking about the fantasyland expansion at WDW (before it opened).
The imagineers from Universal are about bursting with glee and excitement of the space they have created for guests, the detail that abounds EVERWHERE, while the Disney suit drones on about a freakin fountain. Even he appears bored talking about it. This sums it up.
Its not that I think Disney does not have talent, they wrote the book on it really. But they have been leashed by the bean counters, who used the money to make them lots more money in the form of magic bandits. (ok, I am totally stealing that phrase from another diser on these boards, I will have to go and find out their name and post it here for credit)
If Universal's marketing team was half way decent, Disney would be in for some serious competition. Its all good news for Disney regarding this though - they have created marketing imagineers that have taken over the attraction imagineers, and these guys are the cutting edge, blow you out of the water brilliant.