I have to warn you, I'm not particularly sophisticated in my appreciation of art.
One artist whose work I enjoy is Robert Gould, who did much of the cover art for the 1980's paperback reprints in the USA of Michael Moorcock's fiction. I think his covers for the Elric books conveyed the not-quite-human aspect of the Melnibonéans in those stories very well.
I also enjoy Geoff Hunt's work. I became familiar with it from the beautiful covers he did for Patrick O'Brian's Aubrey and Maturin novels.
The Pre-Raphaelites are interesting.