Originally posted by D1N0 When you crop in post you can get the maximum amount of pixels out of the image circle. sometimes only the far corners are black so a aps-c crop would leave out a lot of usable pixels. How sharp the corners and borders are is lens dependent.
^^^^THIS!
And it really depends on how you define "best resolution"
If best resolution means:
1) pixel peeping the center, then it does not matter;
2) pixel peeping the corners, then shoot FF and crop until the corners are acceptable; or
3) total number resolution for the largest possible print, then shoot FF and crop until the corners are acceptable.
Generally speaking, shooting FF and cropping in post provides the most flexibility to get the best out of image. But it does mean buffering and storing larger files and foregoing the higher burst rate of the APS-C crop mode.