Everyone you talk to says you should almost always shoot in aperture priority and, honestly, I’ve done the so for years. But recently, I’ve had a bit of a change of heart in this matter.
Yes, by shooting in aperture priority you control the artistic look of the shot, but you may not always find that your images are sharp. For the past month or so, I tried a bit of an experiment (for me, anyways). I’ve been shooting my street photography almost exclusively in shutter priority. My starting point is 1/125. Why, you ask? Here’s my reason… sharp images in any light. People are always moving, so I know, if I shoot at 1/125, the image will be sharp. If I find a shot where I must have shallow depth of field, I’ll lower the shutter speed to open up the aperture. If I need a higher DOF, then I’ll simply increase the ISO to get the aperture to close up a stop or two. I’ve found that I’m getting more sharp images and can just as easily adjust the DOF on the fly.