What is the best way to clean old fret wire?

What is the best way to clean old fret wire?

There are lots of methods touted online, from steel wool, to the fret erasers sold by Stew Mac, Frine fret polish made by the Music Nomads, a fret polishing cloth, and so forth.

I am not dealing with really crusty, rusted frets, but just some that are discolored from age.

Any suggestions?