Least favorite: moist. That's got to be one of the ugliest words. It connotes uncomfortably damp conditions, and if a girl says it, it's been to known to kill boners. Favorite? Gedankenexperiment comes to mind. I also think mellifluous is self-referentially apt. Apt is another good word.
I really don't get what everyone's problem is with "moist." Then again, I agree with ericblank that "cellar door" is overrated. It probably wouldn't be such if people didn't love quoting Tolkein so much. If he had just been able to keep his damn mouth shut... ;)
Words are arbitrary, but moist just doesn't hit me right. Not to get to raunchy, but it makes me think of an old lady getting turned on. And cellar door is Tolkien? I thought it was another author's favorite (a la Donnie Darko).
The internet tells me that while Tolkien lauded the phrase, he did not originate the complimentation. which I find interesting of course. Apparently many people like it. Sadly I've only seen Donnie Darko once and a long time ago, so I'm missing your reference.