Dinosaur Comics!! Cyanide and Happiness!!
In all seriousness, though, I like the art for Scary Go Round.
(I think that the art for XKCD is, while hardly spectacular, absolutely essential for the analytical state of mind portrayed in it. A funny nerdy comic that can look like a free-body diagram.)
Better Days and of course Sam and Fuzzy both have pretty nice artwork; Sam and Fuzzy feels a little goofier a la JTHM based on the larger facial features and dramatic shading style, while Better Days is a logical continuation of art from the old 90s furry comics a la Sonic the Hedgehog and maybe Swat Kats. Of course, Naylor does some, errr... "funkier" stuff as well.