I had a relatively easy decision to make. I finished a sweater and couldn't decide which buttons to sew on it. I asked for help on Facebook and wound up breaking my brain and writing the following post:
I feel that the yarn has a sort of wholesome authenticity to it and perhaps the deer buttons which not only are made of a natural material but also have a naturalistic, even primitive motif would more logically coordinate with the overall gestalt of the sweater. However, the other buttons, plastic, with a contemporary motif, might create a pleasing duality, or even engage in a dialectic conversation with the sweater fabric.
If you'd like to engage in this process, or see the sweater and buttons in questions, here ya go:
http://www.facebook.com/media/set/?set=a.10100831636994640.3018076.4934365&type=1&l=e10b687d7e