Лучший на сегодня.
Best for today.

I really like Random User-Agent
I can not use the Random User-Agent on a site it is often detect and the site blocks me I would like to know the different settings to be more efficient with.

Thank you for your reply

在Android手机上（大约firefox 63开始）性能不良：我勾选safari on iphone，发现失灵后禁用再启用才会正常。

Works as well as any other User-Agent Swithcer, BUT...!
But the settings are super simple and straightforward to understand and to set up automated switching. That's why I chose this add-on before the other options!

I love this extension as it handles the job of altering UA automatically (set up and forget plugin), but now for whatever reason it doesn't save domain preferences so I have to disable it on custom domains (like youtube else the page won't show) every time. I would like to put 5 stars if this issue is corrected, for me its still the best plugin for that application.

EDIT : I think its just the exception list that is reset; maybe after update of the plugin (autoupdate is on, I will disable it to check)

Works great! I especially love the statistically inconspicuous pool of agents. It still provides a reasonable deal of slight even if you have to set it to a selection of a specific operating system and browser to prevent constant broken websites. For me this is an acceptable alternative to constantly curating a white-list.

The extension works great but broke too many sites so I uninstalled it. Be prepared for whitelisting several sites, otherwise you'll get broken functionality or infinite captchas because the site thinks you're a robot.

Usually works really good. Might break some pages (like YouTube), but it's easy to disable it temporarily if it does. I have one problem with it though, the settings for what browser to spoof isn't saved. I clean out everything when exiting the browser, and somehow this revert the changes back to defaults (to Chrome). Not sure how the settings are saved, but they are lost every time i exit.

Also, an option to change the agent on every reload (instead of just after X mins) would be nice.

[EDIT] Got the settings to be saved by disabling Sync extension settings between browsers. Just a tip if other experience the save problem. The error occurs if you also purging the browser data on exit.

I would continue to use Random User-Agent, however, I had to uninstall due to its breaking of Youtube. With RUA enabled on Firefox, YT's homepage yields only grayed-out slots where the videos should be shown -- obviously I can't interact with anything, let alone watch a video.
This error persists across the most recent versions of both Firefox and Waterfox. I had to disable all of my extensions and turn them on, one-by-one, and in the end, only RUA has this effect on Youtube.

Will gladly re-install in the future if this problem is resolved.