Actually I DON'T think sight reading is important. Certainly not as far as feel and emotion. I was just trying to work with the original phrase "Most versatile". Virtually all the people named here are terrific players in their field, but many only play in certain keys, and certain styles. The "most versatile" guitarist surely should be someone who has DEMONSTRATED that they are "world class" in many areas.
The closest ones to that from what I can see would be: George Barnes, Tuck Andress, Tony Quarrington, and perhaps Bromberg. Although I only saw Tuck play for one hour, my final vote probably would go to him, as I watched him play in several keys, flatpick AND fingerpick, play folk AND jazz harmony, and use several classical positions, and accompany a vocal beautifully.
Now my FAVOURITE guitarist is Doc Watson. Very versatile for a country folkie, but not the MOST versatile.