In my own romantic notion of it being "the last bike I ever buy" it would be awesome to go custom build. I had a local builder I would have liked that to happen with but he shut his doors some time back. A lot of that around here.
Anyway...would probably consider steel, disk brakes, drop bars, braze on for three bottle racks and fenders/racks front and back. Room for ~40's under the fenders. Triple front, anything 10S on the rear (or better) with a mountain bike like gearing. The GT traffic that I currently own checks many of those boxes already and cost sub $500. No real complaints.