Mononoke (not the princess), (scroll ass looking series), the visuals really added to the atmosphere.
Anything stop or claymotion (there aren't that many as far as I know). I'm not into these styles much but they deserve recognition.
Kanashimi no Belladonna, very creepy looking as it should be.
Redline (it speaks for itself), it's the only thing I liked about it.
FLCL (Others tried, none succeded), it gave me a headache just like everything else in it.
Panty & Stocking With Garterbelt (anime that looks like a cartoon), loved the artstyle.
Dead Leaves (the pevious three COMBINED, it's absolutely insane), loved the artstyle.
Mori no Densetsu (It combines virtually every style up until the moment it came out), the only impressive thing about it.
Super Crooks (Makes sense, it's western based and oriented), besides the main girl, didn't care.
1001 Nights ova (It doesn't even seem to be anime), it's impressive.
Aku no Hana (Failed rotoscopy), loved it for how creepy it was.
Metropolis (Odd looking combo of 60s character designs and CGI backgrounds), didn't like it.
Fantastic Children (Failed 60s artstyle in the 00s), hated it.
House of Small Cubes and the other work of the author (I can't even describe it), liked it a lot.
Inaka Isha and the other work of the author (German expressionism ass looking movies), they deserve recognition.
Batman Ninja (For the worse), godawful like everything else in it.
California Crisis (Failed comic book aesthetics), hated it.
Cybersix (Literal cartoonime based on an Argentine comic book), only thing I liked about it.
Anthologies like Genius Party and Japan Animators Expo among others, as they have different artstyles in them.
Hells (Failed imitation of Hiroyuki Imaishi), quite interesting to watch.
Uchouten Kazoku (Fuujin Monogatari character designs in Great Pretender backgrounds), interesting to look at.
Katanagatari (every character looks different, and the backgrounds change according to seasons), weirdly interesting to see but there isn't much movement in it and it ends up being boring.
Mutafukaz (Cartoonime based on western comic about stickmen ass looking gangsters), liked the style and nothing else, it was a very overstuffed movie.
Onboro Film (Anime short that looks like a classical silent movie and a cartoon short at the same time), enjoyed it a lot. Check out Tezuka's other shorts for something somewhat similar though not as distinctive and fun.
Ousama Ranking (It looks like it was influenced by a French comic strip or something), eh, I didn't care about it.
Pluto (Semi realistic looking 60s character designs as expected), they were better in the manga but still fine.
Tailenders (Weak Redline copy), boring.
Yami Shibai (animated kamishibai), interesting to look at.
I did not watch but know of their atypical artstyles:
The Woman Called Fujiko Mine (60s artstyle in the 2010s).
Kuuchu Buranko.
The Layton anime (Makes sense, as they look like the games).
Manga:
Hoshi no Ou Kodomo (you can barely tell it's a manga, it looks like a southamerican comic book instead), loved it like everything else in it.