^Same with me. Coasters are first on the list because CREDZ, but if it comes down to re-riding a mediocre coaster over a good dark ride, I'll re-ride the dark ride every time.
I'm not sure I've really got a favourite type to be honest, other than I'm not a massive fan of shooters unless they offer something a bit more substantial in the way of theming as well.
My favourite at the moment is Mystic Manor, which is essentially a "traditional" style scene/story type, only using amazing sets, ridiculous special effects and high-tech vehicles. I probably wouldn't call that traditional type my favourite overall, but, as an individual ride, Mystic Manor takes the ride type to a completely different level.
I'd probably put those multi-motion tracked things very high up; I mean rides like Indiana Jones and Pharaoh's Fury (though the latter has been somewhat neutered as of late). While Spiderman and Transformers (and Huntik and Darkcastle to a lesser extent) are amazing, with the cars offering a better range of movement, I much prefer to be immersed in 100% physical sets rather than 3D screens.
I love a decent dark boat ride as well, with the best being Pirates of the Caribbean, Sindbad (Lotte World), Sindbad's Storybook Voyage (DisneySea - one of the most underrated rides out there; it's amazing) and Madagascar: A Crate Adventure.
The thing I like about dark rides in general is that you really don't know what you're going to get until you try it (unless you're a dreadful person who spoils it for yourself through POVs beforehand), and, with a decent one at least, re-rides will offer up different things that you might not have noticed before.