? is often given an almost mythical status, so I found it very refreshing when I was made aware of the ? movement that argue that ? = 2? is a much more natural constant.
There are lots of good arguments in favour (do follow the link above), and I’m definitely a convert.
However, as Stewart Russell pointed out to me on Facebook, physicists already have other uses for ?, so perhaps a better symbol could be chosen.
I would propose the Georgian letter ? (pronounced tari), which doesn’t seem to have any uses in maths or physics.