I am going to throw out a 3rd - less known option....
Arrowroot powder. It is found in all of the natural foods stores. It adds no taste to anything - and unlike flour, it will not cloud or make clear aces turn opaque.
And...it has
twice the thickening power of corn starch...literally. SO - you have to be careful that you don'e turn a nice sauce or gravy into a jelly....
It is one of those cabinet residents that - if I am making something that I want to remain clear, and maybe I am trying to keep the calories in check...I reach for.