I sit on the fence totally, since I'm a theme park lover, regardless of what it is, where it is, or
who owns it.
Most people who go to US & IOA are the same as me I'm sure (correct me if I'm wrong) - they go for the rides and the entertainment they have to offer, and do the same for Disney.
You do definitely get different 'feelings' at the different parks - I can agree that you can feel the pixie dust at disney parks, knowing they cater for the kids and do their damned hardest to provide them with a fantastic experience. I can also agree that the universal parks can blow your mind with some of the attractions, and you have a total feeling of fun and enjoyment at both.
I've seen a lot of people who are very much "I've got three weeks at disney, how will i fit it all in?" and the mind just boggles at that statement.... and by the same note, i see the same for some who do everything but disney, so this comment isn't aimed squarely at just the Disney DISers! I go for two weeks at a time, and manage to fit in all four disney parks, a water park, both universals, seaworld, discovery cove, busch gardens AND i still have time for chillin' by the pool, shopping and a nice relaxing walk through the countryside. Classic example is my upcoming trip - ten days for the parks, four days for relaxing!
Every park offers different levels of customer service - some offer fastpass/fotl, some don't, some have good food, some don't, some have great theming, some don't (especially here in the UK), some will make you feel special for being there, some won't. Just remember - wear sunscreen. (sorry, sorry, couldn't resist that end line, the way the sentence sounded just needed it

)
I go to Disney, I go to Universal. I go to Seaworld, I go to Busch Gardens. I don't care who runs them, so long as they're safe and clean. I go to have a good time - not once do i think "I wish i went to
x park today instead"
In conclusion (shall i write an epilogue?

), go to the parks, enjoy them,
but don't compare them. They're not run by the same people, in the same way. Of course they're different - that's the whole point!
*gets off soapbox*