How do they differ in the way they sharpen? When would you use one over the other and how much sharpening is usually required and how much is too much?
I just "googled" "how to set DPP by default to 'sharpness' instead of 'unsharp mask' for 5DMkIII images?" and couldn't find the solution to your dilemma. Maybe Canon can fix this in a future version.
Without going into technical details, 'unsharp mask' is contrast based and strongly sharpens edges. 'Sharpening' is a more overall effect, sharpening not only the edges but smaller details too but less significantly. The unsharp masking has quite an image altering effect, significantly boosting apparent sharpness but it also causes contrast changes at the edges themselves, not something I like. The unsharp mask creates more of a 'wow' effect, but the normally sharpened images are more pleasing to look at for longer.
Thanks for your reply. I didn't realize they were different. Hopefully my pp in DPP will be better now.