Hex for me is definitely the best uk dark ride.
The queue line build up, theming, surroundings, story, narration, effects and the brilliant sound track make for a remarkable attraction and one of the few experiences at a Merlin park that is almost on a Disney standard.
That said, I've not been to a Disney park yet ( shock ) which is something I'm desperate to achieve in the near future as the rides there look far superior to the uk in theming, story, experience and up keep (bar a selected few).
Honourable uk dark ride mentions,
X, love the lights sequence, it feels like a night club themed coaster
Spirit Of London, love the story telling/ theming of the ride. Feels like one of those brilliant Tussaud's and Wardley dark rides
Still haven't done Duel or Sub Terra, plus I am still yet to visit Blackpolol where a good chunk of uk dark rides are housed including Valhalla, which I've heard a lot of good things of. My opinion could change if/when I do these rides.
It's a shame the uk hasn't seen many dark rides built in the last 10 years, as considering the bad weather and that most parks have noise/sound restrictions and/or lack of space, these attractiones would be brilliant for our parks and I think chessie and Thorpe at least could do with a decent dark ride style attraction,. I'd rather see a major dark ride than a coaster at Thorpe tbh.
Storm surge dark ride/
Charlie and the chocolate factory (bring back toy land tours)