No one has really talked about how the willingness--or reluctance--to walk on hills influences your choice of C & V gearing. The old Raleigh three speeds had enormously high gearing, with a high of 90-something inches, and a low in the mid-50s, as I recall. That meant you'd rarely run out of high gear on a downhill, but you'd probably end up walking on long steep climbs. People were apparently happy with that back in the old days. Today, not so much--with modern drive trains you can have ultra-high, ultra-low, and everything in between.
How would you gear a singlespeed in the area where you ride? When I had one a few years back (later converted back to geared) I had a pretty low 42-20 setup. That meant I was tootling along in too low a gear most of the time, but it also meant I could struggle up most--though not nearly all--of the hills in this part of Vermont. If I'd been willing to walk more, I'd have gone with a 42-17. If I'd been unwilling to walk at all, even on monster unpaved hills when the road surface was soft, I'd have to go with a 38-30 or something like that, which would have been ridiculous on anything BUT steep hills.
Many people, I realize, live in terrain that's gentle enough (or perhaps are fit enough) that they never have to make that choice.