In one word: works! In more words, not only works, but it's also amazingly tiny, about twenty kilobyes in size (compare that to over 600 kB or even 4 MB of the most downloaded alternatives, that last one expanding to over 21 MB after installed!), and very minimalist. It could be improved with a better interface (the options just pile on each other in the pop-up bubble) and an option to enter custom strings and/or edit current available selections. Indeed, this should go to the top of the list!

This is the best I could find and is almost perfect! The size is ridiculously small compared to other addons with same functinonality.
The only drawback is that for sites who redirects to m.site is not posibble to reset the agent because once changed to Iphone the original site is inaccesible. The only way to reset is: disable the add-on, go to the site, re-enable the add-on and reset.
But anyway great job!

Works well for me...

People goes alway to the one at top, then, the one that trully useful gets unsighted

a tiny add-on just enough for my need