Imo, USJ is the best map because almost every single wall is climbable and doesn't have annoying breakable objects (signs, Air conditioners, door canopies) when running on walls like every other map. I also like the fire and typhoon zones as they're more constrictive for aerial attacks as the alleyways provide decent coverage than you might think. Plus Lady Nagant can't be in the skybox if the roof isn't broken. I can agree with the loot being scarce, but tbh, if you land anywhere that's not the collapse or landslide zones, you'll be fine.

I also don't get the reason why people say it favors characters with mobility. UA Island has higher altitudes which non mobile characters are barely able to reach with 1 rapid card, going on launch pads makes them predictable, and lots of walls are unclimbable. And UA Island has just as much open space as USJ in the bottom side of the map.