Stan Sakai is one of my favorites! 
I have waaay too many favorite artists, so here are a few that I'm loving at the moment.
Doug TenNapel, Earthworm Jim guy who also makes some wild comics. His style is really expressive and seems totally unique and confident, and I appreciate how crazy and off-the-wall it can be.

Lorena Alvarez Gomez is just... unbelievable. She's easily in my top 10 favorite artists. I love her whimsical, detailed, colorful, imaginative art SO much.
Guille Rancel's work is wild, whimsical, and adorable. I want to read stories about every one of his characters.
Loish, for reasons that should be obvious
Elentori because she's outrageous at expressing mood and emotion so perfectly with a style that isn't necessarily perfectly polished, but the sketchiness adds to the charm!