We're trying to make a decision on the device that we want to commit to. We've been bouncing between the PIC and the AVR for a while and feel that we need to pick one to focus on. In my initial research, it seems like the AVR and PIC are pretty much equivalent competing products. I have seen some vague references (i.e. both device families have similar features as well as unique features so the process of choosing one can be daunting) to differences in the families, but nothing helpful or specific yet.
Michael has gathered some great links. We'll likely consider where we want to be in the longer term (guidance) and see if one of the product families fit better than the other.