Fantastic Children
Stop what you are doing right now and watch Fantastic Children. I'll wait.
I had heard so little about Fantastic Children that its superb quality took me completely by surprise. I have no idea why this show hasn't gotten much attention, but the fact that it hasn't is a tragedy (as with Crest of the Stars and Giant Robo).
Fantastic Children has a compelling, original plot involving a group of children who are all born to different households every hundred years. At the age of five, they all suddenly develop white hair and leave their families, seeking each other out. The rest of the plot is nothing like you'd imagine from the show's title or that description, but I don't want to spoil anything.
Fantastic Children is beautifully animated, too, though you wouldn't suspect it from the simple, almost retro character designs. That style fits, though, and the artwork is consistently well-detailed and fluidly animated. There are no sweat drops or deformed characters, either, though that may also be due to the fact that the show is nearly devoid of comedy.
The voice acting in Fantastic Children is quite passable, with convincing performances all around. The classical soundtrack establishes mood very effectively, including some memorable pieces such as the haunting ending theme "水のまどろみ" by ORIGA.
Simply put, "beautiful" is the word that best captures this masterpiece. I will remember it for quite some time, and I think you will not regret giving Fantastic Children a chance.