OK, I need to weigh in for NORTHER LIGHTS and LAKE SUPERIOR, the two regionals in Duluth, MN. Team 2530 has been going up there for the past 2 years, and we consider it our home regional despite the fact that there are 3 regionals that are geographically closer.
We have enjoyed very high levels of competition with some great teams like 93, 1625, 1714, and 2052 (many others as well).
The pit area is unequalled anywhere in FIRST. Nowhere else will you have such spacious pits.
Last year, at Lake Superior, was my first experience volunteering as a Robot Inspector. Because there were so many SUPER-EXPERIENCED inspectors there, I had to actually tell them to let me try to help some teams!
Outside of the arena, you won't find nicer people anywhere. If you need a ride, directions, or information, ask anyone you see. They don't even have to be from the FIRST community, they'll still help you. I don't know if Orlando, Baltimore, and NYC can compete with that.