As people have already nominated Gringott's and Dragon Challenge, I might as well complete the trinity: Harry Potter and the Forbidden Journey has an excellent queue, but I didn't like the ride itself that much - it's too noisy and incoherent, flinging you from one Wizarding World monster to the next without taking any time to breathe, while blasting BRRRRRRRRT in your ears the whole time.
Expedition Everest deservers a mention too. The queue is so top-notch it makes it hard for the coaster itself to compete. My aunt hates riding coasters, but she was fascinated enough by our descriptions of the queue that she decided to join us for the next go-around, without actually riding the coaster. It's a queue worth chickening out on, it's that good.
Another shout-out to Colossus at Thorpe Park. I mean, the queue is nothing special, but the experience of standing in line is vastly more enjoyable than that of being on the coaster.