Given that it is the best (and only?) addon that allows to redirect URLs, I have to give it the maximum score.
I use it to redirect to the english version of the websites while being abroad.

It would be even better if it wouldn't require scary permissions.
See:

https://support.mozilla.org/en-US/kb/permission-request-messages-firefox-extensions#w_access-your-data-for-all-websites

The extension can read the content of any web page you visit as well as data you enter into those web pages, such as usernames and passwords.