Privacy

afaik the chameleon extension can randomize the browsers useragent, os and browser tech/version.

Some websites don't work at all if they detect certain OS or certain browsers.

So OP is probably asking which of the OS browser useragent combos to have in the random selection and which to turn off for the best user experience.

It is up for debate whether randomizing the useragent does anything at all: javascript can detect if you try to spoof your OS/browser by changing the useragent (as demonstrated by https://abrahamjuliot.github.io/creepjs/ )