I tend to gravitate more towards some of the darker shows. Tokyo Ghoul was amazing, although it went downhill in season 2 when they cut some of the most iconic scenes (semi-understandable, but TG is definitely never going to be family-friendly).
I started watching Darker Than Black, but I couldn't help but feel that it wasn't really going anywhere after 20-odd episodes.
Hellsing Ultimate is visually striking - because it's an OVA the animation quality is a step up, and again it does a beautiful job of blurring the line between man and monster.
Cowboy Bebop was something I watched a while back, it shows its age but still has its own very distinctive style. If any of you watched and enjoyed Firefly you'll probably like Cowboy Bebop.
Also, not technically an anime, but RWBY has some fantastic action scenes. The background ghost people in season 1 are annoying, but after that it really picks up.