I have been resisting to comment on this thread because the topic is very subjective. Some people love Universal, and some love Disney. They are very different from each other. I am just going to do comparison below:
Atmosphere:
Disney has more of a laid back atmosphere because Disney is always family oriented. From the rides to the merchandises, everything are family oriented. Universal has more of an adventure atmosphere. When you approach the greeter TM at Ripsaw, they will greet you with "Welcome to Canada". Every attraction will have different greeting. Universal tries to make you feel like you are parts of the attraction. The TMs are the storytellers. I never once being greeted by the CMs at Disney.
Rides:
How many rides at Disney actually go upside down? Just one. There are rides that have big drops but only one ride actually go upside down (Rock and Roller Coaster). I am a huge roller coaster fan. I find all of the rides at Disney are pretty tame compare to Universal even though I love all of them. Universal has better rides than Disney with Hulk, Rip Ride Rockit, Dragon Challenge, Forbidden Journey, etc. When you ride the water rides at Disney, you have a possibility of not getting wet or soaked. Not the same case with Universal's water rides. I can guarantee you will get wet.
Entertainment:
Disney has more fireworks than Universal. They also have better entertainment than Universal. There are varieties different shows and parades that guests can enjoy at Disney. Universal only has one firework show and one short parade. They are not always happening every single day. They will have the show one day, and no show the following day.
Event:
I absolutely love the events at Universal. I love the Mardi Gras and Halloween Horror Nights. HUGE FAN of both now. I have been to
HHN for a couple of years now, and I just experienced my first Mardi Gras. Love both of them. Disney has several events that I like but not necessarily love. I like going to the Food and Wine Festival because I am a foodie. I like the Star Wars weekends even though I am not a fanatic of the franchise. The
MNSSHP and
MVMCP are okay in my eyes. I am way too old to go trick or treating. I felt extremely uncomfortable doing it.
Merchandise:
I love the merchandises from both parks. Who doesn't love a Mickey hat or a minion's shirt? They are lying to themselves if they say no. The prices are expensive, and you have to have self control before you break your bank balance buying a lot of merchandises. I particularly like all of the limited edition merchandises because they are limited. If you are broke and need money, you can sell them on ebay for quite amount of money.
Transportation:
I have to say that Universal has a better transportation for on-site guests because there are so many ways for guests to go back and forth from the hotel to the parks. They can walk or take the 5 minute boat ride or take a shuttle ride or pay the rickshaw. The close proximity makes it more convenience for us as guests. Disney is more spaced out. You can't walk from MK to HS or from MK to AKL. They are just too far away from each other. I was waiting for more than half an hour to take the bus from HS to MK under a hot Florida sun. The family in front of me was not amused at all. Not very reliable. There is no bus from any of the parks to downtown Disney.
Food:
Both are terrible. I rather eat outside than eat inside of the parks. They are so overprice for decent meals.
Accommodations:
Comparing Disney hotels to Universal 4 hotels are very hard. I have stayed at both sides, and I like them all. My favorite Disney hotels are POFQ, AKL, SS. I have stayed at RPR plenty of times and HRH one time for HHN, and I had a fantastic stay at both hotel. You can't beat extra magic hours at Disney or the unlimited express pass at Universal.
Interactivity:
Disney has more interactive experience. SOTMK and the Pirate's game are just some of the interactive experiences that guests can do inside the park. Disney also launched My Disney Experience app ahead of Universal new app. Universal is in the process of launching an interactive wand experience inside HP islands. Disney is a step ahead of Universal when it comes to technology interaction.
So who is better at the end? Who cares. Let them compete with each other. The more they compete, the better for us as guests. We will have more amazing attractions, entertainments, merchandises, better food, etc. We go to these parks to have fun. There are plenty for us to do in each park.