Well, my favorite is "Robots and Empire", but that's because it is the one that I chose to read first. Ayn Rand is another one of my favorite authors. I think she died, and I didn't know Isaac Asimov is out there. I haven't checked up much on either because my soul has been on the back-burner for 35 dog-years. In other words, my girlfriend sucked out all my motivation to continue 80% of the activities that I, once, enjoyed.
I've never even heard of A. E. Van Vogt.
Reading is like bowling to me. I'm good enough to do it, but I can't find anyone to help me indulge in it.