I can eat almost any burger - even the theme park quick-serve cardboard ones...it's just an easy, filling lunch grab. However, for burgers I really really love, I tend to prefer flame-grilled, with a decent char on the outside, rare inside, bun to be non-potato bread, and a sharper cheese like a cheddar nicely melted. The toppings and sauces can vary for the theme of the burger - but those preparations, breads and cheeses would make the burger higher on my list.
I do like smashburgers and other grilled burgers and have had some great ones, but if it were down to what I consider burger perfection, it would be flame grilled and rare.
Geyser Point's bison - definitely a good burger and one I get regularly. D-Luxe is pretty decent for a fast-food-type spot. The Bar Riva burger was very good. I do love Steakhouse 71's stack - the pork belly is what makes the difference there.
I haven't seen this one mentioned here, but I thought it was a pretty decent burger - City Works bacon cheeseburger...good cheeses, nice blend on the meat.
For the cardboard quick-serve in-park burgers, which are generally all the same, I found Connections had a better quality burger with a nicer blend on the meat, and some very interesting options - the French Bistro burger was solid.
Raglan Road's OMG burger was a definite winner for me - great tastes, very high quality ingredients (great bacon) and whiskey BBQ sauce.
I definitely appreciate The Fountain - since Boardwalk lost all of its quick lunch food options after ESPN and Big River closed - it's just a classic 'diner' - decent burgers, fries, shakes, etc.
Some missing burgers of the past...
One fast-service joint's burger I really miss is the battered, deep fried burger at Cooke's of Dublin - it dropped off the menu sometime last year - that was a unique one I really enjoyed - it basically was their dubliner burger but dropped in the batter for their fried fish - paired with the garlic mayo and dubliner cheese, it was something really unique and tasty.
I also miss Maya Grill's queso fundido burger - there are some other spots that had one too - Rix and Paradiso - but neither were as good in my opinion.
Riverside Food Court's Bayou burger - better beef blend than the usual park burger, with a tasty cheese sauce.
Kona Cafe's crispy cheddar burger - loved the charred cheddar and really nice thick bacon, with interesting sauce/seasoning on the burger.