At the end of the day, I'd pick country.
In my limited time driving, my route was almost a perfect mix of everything. I drove about 165 miles, about 100 stops, and about 15 pickups. PC went out full, and I brought it back to the building full. I literally had just about every delivery type besides high-rises. I had a high-traffic town portion....3 residential neighborhoods, an entire industrial park to both deliver bulk and pick-up, plenty of other commercial, trailer parks, 2 apartment complexes and then about 35 stops in the country.
It all comes down to preference I guess. I can see how country would be miserable during winter months....and I HATED the dirt roads with about 15 mailboxes at the entrance....and not a single number on any house when you drove down it. But, I loved being able to drive around the country...the scenery, being able to cool down when it was 100 degrees, and getting a break after all of my bulk I delivered in the industrial park. Customers were awesome. No traffic at all. I hate traffic. Loathe traffic.
The city/town portions of my route were fine in regards to staying busy and getting time to go by faster. I can also appreciate why it's better on main roads during the crappy weather events.
I'd take a full country route any day of the week, though.....no questions.