I can think of a few. Let's see.
One of my favorite manga artists ever is Takeshi Obata, even though I don't always like the manga he's part of because others are responsible for the writing. I don't really like Death Note and I've only read a bit of Bakuman. My favorite thing of his is actually Hikaru no Go where he teamed up with someone other than Tsugumi Ohba for the story. You can actually see his art mature in that one, it's great.
Miwa Shirow is another mangaka with a really great style. His manga is called Dogs Bullets & Carnage and it looks like
this. He's not really big on backgrounds, but I love the way he draws people.
Another one of my personal favorites is Shinobu Takayama, author of Amatsuki and Haigakura. At first her art looks a bit typically shoujo, but I think her character designs are really nice and when it matters the art can really bring out the fantasy element in her stories and how rich and colorful the world the stories take place in is.
Link &
link. Both manga are pretty cryptic and hard to read though, so I guess that's a downside.
The Breaker is also a thing with pretty stunning art. It's a manhwa about an underground group of super powered martial artists and it looks like
this. The story is really good too and I just remembered I'm about 1000 chapters behind on its sequel.
I think that Bleach actually has really great art too, but you know, it's Bleach.