The UK passport is the best in the world in every ranking:
https://www.linkedin.com/pulse/top-10-most-powerful-passport...
https://www.linkedin.com/pulse/top-10-most-powerful-passport...
In addition to the additional metrics you mentioned, perhaps yet another to take into account is how hostile natives feel towards you when traveling in certain parts of the world--up to and including harassment, kidnapping, and (in limited locations) beheading risks.
In places (even here in Europe) where people tend to by default assume good English speakers to be American, I get better treatment by managing to convey that I'm not.
Any other bits?