Well, I really do like Atlas track, but I really don't like Atlas switches. Also, Atlas track is way overpriced and hard to get nowadays. Next on my list is Ross track and switches, and I combined it with Gargraves flex track.
Ross switches are the top of the heap, and their sectional track is excellent as well. Gargraves works seamlessly with Ross track and switches, and Gargraves offers flex track, which I used extensively.