I want to make an app which involves repeatedly giving users two options and having them select the one they like better. Is there any icon or symbol which would intuitively represent this concept, which I could place next to the word "compare" on a navigation button? I'm wracking my brain and can't come up with anything, which suggests that there may not be a natural icon choice...
I found this "primary diff" icon from the KDE icon theme which uses a question mark to represent a choice between 2 options:
It is available here and is free for personal and commercial use.