When I first saw this thread I thought it would be easy to answer. I love art (majored in Fine Arts in college) and have favorite artists. But when I started to really think about it, I realized that I had never really analyzed why I like the stuff I do.
I don't think the subject matter of the paintings is as important to me as the technical aspects that were used -- the colors, the brush strokes and paint texture, the details (ha! Typical, right?) of such things as how well hair and fabric are portrayed, or how transparent the water is or how good the perspective was done. In particular I think I'm attracted to the lighting and shading. Some of my favorites are Caravaggio, Rembrandt and Vermeer. What I like about all of them is how they use light and dark (chiaroscuro) in their works. You can see from what direction the light is emanating, and how it affects the subjects in the work.
I enjoy some Impressionism, particularly Monet, Renoir and Van Gogh. I got to see some of their works during a tour of pieces from the Metropolitan Museum of Art. Monet's "Girl with An Umbrella" and Van Gogh's "Cypresses" completely blew me away. In both cases I could actually FEEL the paintings -- the wind, the sun...it was like I was in the paintings, experiencing it like the artist did. Not a fan of Picasso, Chagall, Rauchenberg and others whose works to me look like something done in kindergarten art class. Nor am I into "Pop-Art", such as Andy Warhol and Roy Lichtenstein.
As far as people in works of art are concerned, it kinda depends. I am with most of you in that I'm not a big fan of portraits, except when they are exceptionally well-done. I do like, however, naturalistic works where the people are going about their daily lives -- gardening or cooking or sailing or whatever. As for true Abstract Art, once again it depends. I have been entranced by works that are nothing more than strips of color, but then seen works that look like somebody tripped up against a canvas when they were taking out the trash.
In my own photos, I almost NEVER include people in the shots. I take pictures of wide expanses and sunsets and architecture, but most of my pics are closeups of flowers, mushrooms and insects. A friend of mine said once that you should always include yourself or people you know in vacation pictures; otherwise you might as well just buy postcards. I disagree, because the pictures are for me, not for other people, so I don't care whether anyone believes I was actually there or not. I know I was, and I have beautiful unobstructed photos to remind me of it.