I will suggest artists to you, and if you would like to know where to start, I can suggest specific comics by them too.
Are you familiar with Chris Ware? I do suggest his work. Also, Burns, Tomine, Clowes for the more existential American indie comic.
You could do worse than read Moebius, Bilal, Pazienza, Manara, Liberatore... so on. There's just a huge range just right there that is inexhaustible.
Alberto Breccia is our lord and master he's done all that the above did, before them, alone, while struggling to feed a family and help a sick wife with the little money he made from his work in Argentina. and he did even MORE. The true master, the unsung genius of the field.
Speaking of genii If you haven't read Will Eisner, you simply must.
Robert Crumb, surely.
Dave Sim went halfway crazy to give to you comics like you never thought there could be.
Paul Chadwick certainly.
Craig P.Russell and Barry W. Smith are my biggest inspirations about the beauty in human forms (perhaps Neal Adams too!).
Geoff Darrow for detail.
Mark Schultz.
Do you want manga artists too?