One I can think of is The World of Golden Eggs.
Aku no hana
Angel’s egg. Though it’s more so the expressions, color pallet and overall vibe that is unique rather than the animation itself (for its time the animation is pretty normal looking).
I thought Ping Pong : The animation was pretty unique. (so unique some of my friends wont watch it because of that and while I dont watch sports anime, I loved it)
I didn't watch Ping Pong but Arc did. I would check it out sometimes because the animation style was so different.
Super Milk-Chan. It feels more like your average American adult comedy, but still feels quite refreshing to watch.
This one isn't super dramatic of a style, but it's unique enough for attention. The art style seems half-chibi, if that's possible. Very vibrant colors sometimes contrasting with pastels. Very cute anime, fun, dark at times.
ako no hana is THE strangest looking anime, but as far as stylized animation goes, Kick Heart is one of the most artistic animes out there