Should I use the side prop or centerstand when I park?
Use the sidestand for everyday parking. The centerstand is for storage and maintenance.
The sidestand creates a larger tripod than the centerstand does. It is more stable for parking on the street. The centerstand creates a smaller parked footprint and takes the rear wheel off the ground; this is the better position to have when doing work on the bike, and sometimes when parking it at home. If you can use the sidestand at home, though, you should, as the bike is less likely to fall over that way.
For more centerstand usage information, click here.