Hah. I jest.
It is impossible to pick a favorite Amendment. So many are foundational.
I think too many here are placing stock in the 2nd Amendment, when our liberties are much more straightforwardly safeguarded by the 14th. 14A’s Due Process and Equal Protection Clauses are the foundation of a lot of civil liberty-oriented case law.
I agree with your point about the Constitution being changeable by design. And I’d add that the fact we haven’t had a new Amendment in awhile is a symptom of the failure of the political imagination of our generation.
If I had my druthers, I’d pass an amendment abolishing the Electoral College or reforming it to take away winner-take-all allocation of electoral votes. We’ve become far too beholden to the whims of voters in a small number of swing states, and it’s ridiculous that candidates pretty much ignore the nation’s largest population centers (NYC, LA, SF, Chicago, Houston, Dallas, Atlanta) because they happen to be located in deep red/blue states taken for granted.
We did pretty much this with respect to the popular election of U.S. Senators in the 17th Amendment, and we can do so again.
https://en.m.wikipedia.org/wiki/Seventeenth_Amendment_to_the_United_States_Constitution