*Chuckles* I ended up going with "Scent" and "Size" myself. Though in all honesty it was a pretty tough decision. Because I enjoy every single one of the options listed. ^.^
But I've found that I enjoy the natural scents that surround feet/footpaws more and more as time goes on. Because on one paw they can be tools for humiliating a partner or enemy. While on the other paw, they can be a gateway for showing deep levels of affection. Both of which are scenarios that I fantasize about myself.
And then of course the size one is a given. Though I imagine my ideal sizes are a bit more extreme than most. Seeing as how I like for my footpaws to be as big, if not bigger than my entire body. ^.^