My favorite one is Lichtenstein (he mainly worked in inks and did pop art).
I got interested in his art back in High school. I have one of his smaller pieces called "The enemy would have been warned" One of my favorite works by him.
I would like to own more, but his works are now a big thing in the pop art revival that is going on right now. So the prices for his works are going through the roof.
Oh well there is always lithographs of his works.