If I could have only one speaker, I would take somethimg neutral, but I definitely like to play with speakers that are not neutral, especially when I am using old amps and old media. I really like horn speakers, and full range speakers, especially eficient ones in big boxes.
If you want good frequency response, JBL speakers with big drivers and lots of cone area would be the best I think. You can get efficient ones with horns too, which would be about perfect for good rock reproduction.
If you want some coloration, maybe try a Crites Cornscalla, Klipsch Cornwall, or Klipsch Heresy. Same idea, but a little more retrospective. Big cones and horns.
Sort of depends on what you are going for. As I said, I would not choose colored FR speakers except to supplement more transparent speakers in the stable. Some of the JBLs can do it all. Klipsch RP 8000F might be good all around too, but I don't know for sure.