There are really 3 kinds of stop signs:

Reminders, found at the intersection of a smaller and larger street, with the hope that you stop and look, before proceeding.

Sorters, these are found at intersections of streets that may seem equal, but may have different traffic flows, usually the less busy street has the stop sign, if traffic is equal on both streets, a 4 way stop may be used, the idea is to sort out the traffic.

Political stops, these are multi-directional stops where the only purpose of using a 4 way as opposed to a 2 way stop, is political in nature, traffic flows and street size are often vastly different, but rather then ticket speeders, they install stop signs to slow down the traffic. In theory this should work, it really doesn't though, because lead foot drivers will simply use lots more gas, and create a lot more pollution to get back to cruising speed.

I usually stop for stop signs that are reminders and sorters, although when you get the 27th political stop within 1km on a ride, sometimes, I will admit to going slowly through, providing there is NO cross traffic. This will be in a gear I am comfortable stopping in though. Stop lights, always stop, too many cagers see a green light and don't look for traffic. The first thing you learn though in any kind of defensive driving course is to expect that the other guy will, given the chance, do something stupid. I apply the same rules when riding.