Comic Book Resources has a list of the best 50 artists of all-time as voted on by readers. Here's the list thus far (they're in the Top 10, doing three per day now, apparently); the ones I'm familiar with are in bold ... and my commentary is in italics. I'll update the Top Ten, as CBR does, in new posts.
50 Jaime Hernandez – 213 points (3 first place votes)
49 Sean Phillips – 222 points (1 first place vote)
48 Francis Manapul – 230 points (8 first place votes)
47 David Finch – 242 points
46 Doug Mahnke – 249 points (5 first place votes)
45 Mike Deodato – 251 points (5 first place votes). Realistic artist, although his men are way too muscular and females way too curvaceous (see the Black Widow at right, for example). Did quite a bit of work during the wretched "The Crossing," where Iron Man became a teenager.
44 Steve Dillon – 253 points (2 first place votes)
43 Paul Pope – 255 points (3 first place votes)
42 Ryan Ottley – 261 points (7 first place votes)
41 Mike Allred – 262 points (2 first place votes)
40 Adam Hughes – 273 points (3 first place votes)
39 Alex Maleev – 276 points (2 first place votes)
38 Dave Gibbons – 278 points (1 first place vote) Perhaps best known for his work on Watchmen, in my opinion Gibbons is just a middle-of-the-road artist -- not great, but certainly not bad, either. He also teamed with [writer] Frank Miller (#8 on the list) on the superb Give Me Liberty and its sequels.
37 Tim Sale – 283 points (5 first place votes)
36 Joe Kubert – 285 points (4 first place votes)
35 Steve McNiven – 291 points (4 first place votes) Has done a lot of modern work, notably on various Avengers titles. Pretty good stuff.
34 Barry Windsor-Smith – 294 points (3 first place votes) Very gritty work with a quite realistic touch; some of his early work, however, featured way-out of proportion anatomy. But that same work was quite "cinematic" in approach. I loved his work on Machine Man 2020.
33 Jim Aparo – 298 points (4 first place votes)
32 Moebius – 305 points (10 first place votes) Didn't this guy only do posters??
31 Gene Colan – 335 points (4 first place votes) Gene set the standard for the "cinematic" approach to comics. His panels were angled in such a way as to make it feel as if you were watching a film. His work on Daredevil and Iron Man in the 1960s was sensational.
30 Ivan Reis – 385 points (5 first place votes) Very realistic contemporary artist with a John Buscema-feel to his work.
29 Arthur Adams – 388 points (6 first place votes)
28 Olivier Coipel – 408 points (6 first place votes)
27 Chris Bachalo – 429 points (11 first place votes)
26 Gil Kane – 435 points (3 first place votes) One of the masters of the Silver Age, his realistic work perhaps reached its zenith with Amazing Spider-Man #s 121-122, the death of Gwen Stacy. Check out Kane's "signature pose."
25 David Mazzucchelli – 438 points (5 first place votes) Incredibly detailed and realistic artist, he's perhaps best known for his work with the aforementioned Frank Miller on Batman: Year One and Daredevil: Born Again.
24 Walter Simonson – 449 points (7 first place votes)
23 Jim Steranko – 467 points (5 first place votes)
22 Brian Bolland – 489 points (9 first place votes)
21 Bill Sienkiewicz – 493 points (10 first place votes)
20 Bryan Hitch – 495 points (6 first place votes) Incredible contemporary artist perhaps best known for his work on Marvel's The Ultimates and Wildstrom's The Authority. Hitch masterfully extrapolates on the "cinematic" approach perfected by guys like Gene Colan and John Buscema.
19 John Romita Sr. – 505 points (7 first place votes) Although a stalwart Marvel Silver Ager, I was never overly impressed with his work. His women, in particular, all looked the same, and his action scenes were too "wooden."
18 Will Eisner – 512 points (10 first place votes)
17 Stuart Immonen – 535 points (10 first place votes)
16 John Buscema – 593 points (17 first place votes) Buscema is a god among men in the comic realm. His Silver Age work was beyond phenomenal (Avengers, Silver Surfer, Fantastic Four) and his sense of realism and cinematography were unparalleled. (At left: Buscema details how the Silver Surfer first got his powers from Galactus.)
15 Alan Davis – 678 points (14 first place votes) Another superb contemporary penciller, he perhaps is best known for his work on Excalibur and more recently his stint on The Avengers.
14 Darwyn Cooke – 686 points (21 first place votes)
13 John Cassaday – 728 points (13 first place votes)
12 Steve Ditko – 749 points (5 first place votes) Ditko is a hard guy to pigeonhole. His work on the beginnings of Amazing Spider-Man has to be his best-ever; his other stuff, in my opinion, is easily forgettable due to its ridiculous overly cartoony nature.
11 Mike Mignola – 810 points (12 first place votes) I've never read his Hellboy, but I've seen some of his other stuff. He has a very cartoony style, but it works well because of his incredible cinematographic approach.
10 Alex Ross – 822 points (21 first place votes) You really cannot get much better than Alex Ross. Why he is only #10 is a travesty. Just scan through Kingdom Come and Marvels and if you're not literally gasping at how breathtaking his paints are, well, you're a dolt.
9 John Romita Jr. – 846 points (13 first place votes) Sorry, but the fact that JR Jr. is ahead of such giants as John Buscema, Gene Colan and Alex Ross makes me want to tear my hair out. If Romita Jr. doesn't have the right inker, he's a mess. Period.
8 Frank Miller – 897 points (10 first place votes) Miller is just an OK penciller but his action sense is hard to top. Just check out his work on Daredevil to see what I mean. He's a much better writer, in my opinion.