I have never understood the love for the Girl in the Fireplace. Never.
I think the story of a man who is deeply isolated because he just doesn't know how to have a relationship, who then encounters a woman who gets to know him incredibly intimately without him meaning to let her into his heart, is deeply moving. As is, for that matter, the way he loses her at the end.
Mind you, while I rate V&tD highly, I dunno, there's a couple of good TNG eps in s5 and 6. But it's definitely one of, if not the, best Who eps.
I can't think of a single episode of Star Trek: The Next Generation
that is as well-written and well-acted as "Vincent and the Doctor." The characters on TNG are far too shallow and two-dimensional to even compare.