It doesn't matter. Actually those plugins are straight up counterproductive.

The best user agent is the one that offers them the fewest identifying bits. In other words, the user agent of the most popular version of Chrome. The ability to set it to "anything we want" is actually a trap. What we really want is for everyone to use the exact same user agent so they can't tell us apart.

If everyone has the same user agent, it's nothing but a waste of bandwidth and it should be removed. Google is actually achieving our objective here.

Well yeah, they have a pre-configured set of choices, e.g. "Chrome on Windows" but you can do something custom too, if you want.

Firefox has plugins to set your user agent to Chrome.

Pointless. Firefox should just pretend to be Chrome by default without the user having to install plugins or even do literally anything. As should all the other browsers. Anything that leaks out the fact it's not Chrome should be considered a bug and fixed.