"I would like to second this question. There are plenty of Perfectly Adequate art jobs, but I've yet to find real knockouts like there are in the the hero and suspense books."
My hunch is that working on comics for licensed Western stars kept artists from doing really stylish work, as it was probably not a good idea to out-shine the stars you are portraying or connect them too much with an individual artist's style. Plus there were probably additional movie studio minions who had to sign off on the work, but who didn't know s--- about what made for good comics. (Granted, that's a lot of suppositions on my part.)
I will admit a certain prejudice against Fawcett comics. While I bow to the quality work of CC Beck, Mac Raboy, and co. on the various Capt. Marvel family comics, I've never been a big fan of the run of the mill Fawcett books. Their printing and coloring seemed sub-par and I seem to recall that there was some curious linkage between Fawcett and Charlton, the latter not one of the favorite publishers either.
Still, I'd love to discover some Fawcett westerns that had unexpectedly great art, if such exist. Bob Powell and George Evans did some quality work for Fawcett's horror & suspense titles, but I don't think they worked on the western books. Correct me if I'm wrong.