Interesting question!
Performance is the key for me. However, I break that down into several aspects:
1. Ease and quality of lather
2. Slickness
3. Cushion
4. Ease of clean up
Scent, post-shave feel, skin conditioning, etc are of secondary importance for me.
That looks like a good list for me as well. Slickness tends to be a non-issue for me as I only use soaps that have been highly recommended here and so far none of them are lacking in slickness.
I have tendonitis in my elbow, so ease of lather is more of an issue for me than many.
Cushion could be called protection on my list. Weepers have all but disappeared since I changed to top tier soaps. And yes, I believe there are shavers who use $2 soap and don't get weepers - but they don't shave my face.
I use unscented MdC as I'd rather enjoy my scent from cologne and I am afraid of having an unpleasant scent in a soap that lasts me 375 shaves.
I finish every shave with Thayer's WH followed by moisturizer, so post shave feel is secondary there as well.