Peter:
Good question; I'll take a shot.
For R.B. Harris, it's someone who is roundly criticized -- often fairly, I think -- for designing courses to fit maintenance practices (e.g., making the width between bunker and green the size of contemporary mowing equipment). But an early design of his, dating to the 1930s (Janesville Riverside, a muni run by the city in southern Wisconsin), shows plenty of interesting use of the terrain, interesting greens, and some true quirk (a 95-yard par 3 straight over an oak tree, a 185-yardish par 3 with a 3/4's collar around the backside of the green that keeps balls from flying over the backside). I've played some of his older courses, and while I think they are OK, they don't quite hold the interest of this interesting early work. It's short by today's standards, and has little room to expand. Still, it's a fun course; I've been seeking out other early Harris courses to see if they match Riverside.
Watson seems to fly under the radar, compared to other classic-era architects, perhaps because he was less prolific than some of his contemporaries.
I included Bendelow because so much of his stuff is still around, and -- although there are lots of reasons for courses good and bad to come and go -- I think it says something that so much of what the admittedly prolific architect designed survives. His original nine at Old Hickory CC in Beaver Dam, WI, is the foundation of a very good course that flies well below the radar.