For me the main things are visibility, lane width and comparative speed of overtaking traffic.

Each type of street has it's own challenges. One of my least favorites is the busy intown neighborhood street lined with parked cars, speed limit 30.

One of my most favorite is the four-lane, one-way street downtown that allows me to grab an entire lane to myself (since it's too narrow to share.) Plenty of room for cars to take one of the other three lanes. Speed limit 35.

But all in all, I like lots of trees and fewer cars.