The list is long. Excerpts would be Bosch, Breughel, Rembrandt, Richter … And I cannot believe I am the first one to mention Lucien Freud. Vilhelm Hammershøj is one of the truly great Danish painters, and so is Asger Jorn - I really like Le canard inquiétant -the last image on this page..
N.C., Andrew and James Wyeth. Partially because I grew up in the Brandywine River valley and they were the so called ‘locals’. I love the turbulent skies in Turner’s painting.
Zoe, now you’ve got me a little jealous I’m so far from Maine. I’d love to see the original locations.
Oh, and how you doin’? 
Expressionist Franz Marc.
Heh, never thought about it. I’m not at all versed in art, but I did like SciFi/Fantasy art a lot when I was younger. I’ll say Larry Elmore. I particularly likethis one, I have a print of that painting on my wall.
VanGoch,Breughal and Bosch,Canaletto,Pisarro,Dali.
As genres,Ilove PreRaphaelites,Surrealists and Dutch 18th c.
If I hadn’t known about Bosch, Bruegel would be amongst my faves, but much of his stuff is too derivative for me to respect him much as an artist (although I still like his paintings as paintings). My second favorite after Bosch is Goya, and if I ever go to Europe I’m going to the Prado!