i like obscure painters (or graphic artists) that have yet to make a name for themselves. i like Tado, because they are weird and wacky (and currently one of their posters can be seen adorning the wall of the tv show The IT Crowd), they usually work in graphics, but have been known to pic up a paintbrush. i love Tara McPherson too, i have 2 of her prints (one official, signed & numbered, the other not, for Dismemberment Plan and Beck)
i love these guys:
http/mooncalfe.deviantart.com/ - comic work, excellent characters, works in ink, paint, eyeshadow...
http/kolaboy.deviantart.com/gallery/ - a painter, you'd think he was faking the paintings they look so real, then you see how weird the people are and what they are doing, it's like woah!
of all the old favourites, i have a soft spot for Edward Hopper, i like the warm bleakness of his paintings. they way they look so real.
i don't really like to harp on about old masters, i wouldn't ever be to afford an edward hopper painting. but with urban graphic artists, or artists on devart, those are within reach!