If you had asked me this time last year what the best all-around bike for the average person was I'd have answered without hesitation, "A randonneuring bike with 35-42mm tires, fenders, a front bag or medium sized basket, and generator powered lighting system." That's a fairly specific answer for a general question, but it is an answer arrived at after much experience on the roads. And to be fair to myself of a year ago, it might be the best general answer considering the typical infrastructure of a typical US city.
It certainly held true in Dallas, which like most young cities, suburbs and exurbs has developed under the assumption that automobile is and will always be the primary form of transportation for the vast majority of residents. Accordingly, the distances between home, work, and daily destinations in such places are longer than, well . . . any other living arrangement in human history, so anyone attempting to use a bike as primary transport will be forced to travel long distances on roads made for fast automobile traffic. These roads will have typically have infrequent and visible intersections with buildings set far back from the road, often separated from the road by a parking lot.
Getting around in such a world is best on a rando bike. The semi-upright position affords a good enough view of the road while still putting the rider in an efficient enough position to bring the large muscle into play while pedaling, which helps cover those long distances. Those who want to be even more efficient can easily change their position by dropping their bars and changing the fore/aft position of their saddle, which will slightly change the effective seatube angle.
When I moved to downtown Wilmington I noticed that my rando bike felt a little awkward. Downtown Wilmington's layout was built for pedestrians and horses. The blocks are very short, so intersections are numerous. Intersections aren't incredibly visible, because the buildings are pushed forward so that pedestrians can enter easily from the sidewalk. When there are parking spaces they are at the side of a building, not the front, but most business don't have any off-street parking at all. There are numerous cyclists and pedestrians. These features cause car traffic to be much, much slower. But because of the bad visibility and frequent intersections, driveways, etc. a cyclist needs to be constantly looking around. This makes a very upright position desirable. Luckily, my average trip is much shorter here, because almost everything I need to do is within four miles of my house so the only drawback to an upright position (less efficient position and less speed) is not an issue.
Add to all of this the fact that I daily carry a child in a stem-mounted seat (which works best on an upright bike) and my my primary bike has changed dramatically. This realization was humbling and instructive. I found that I slowly made some changes to my bike, and then built a second bike that was very different from the one I'd used to get around Dallas. What I'd cobbled together was a city bike with a very upright position a type of bike I hadn't had previously held in high regard.