YAY a comment
I considered doing it as opposites, but the first ones I did, before I decided to make a series, was precipitation and evaporation, which are perfect thematically for what they do mechanically. After that I decided to just go with what fit best thematically. I intentionally did not make time and aether opposites nor gravity and entropy to keep consistent the inconsistencies, if that makes sense.
All of it is quite adjustable, as far as which two pair together, but only if a proper theme is present.
Also, I don't know if this should cost less/cost more, or affect less quanta/affect more quanta. This is all easily adjustable.