Thanks. What is the most common user agent out there?
Sadly, this is of limited use. Defense against fingerprinting is like herd immunity. If everybody else already has a unique fingerprint, there is not much an individual can do to avoid being uniquely identified as well. At most one can spoof one other unique individual. Plus the EFF recommendation is 'latest Chrome on Windows' which is a moving target.
Would be nice if the EFF site in OP would recommend an agent id to spoof to, at least that would help building a small, but non trivial herd of indistinguishable users. And then a popular extension like uBlock Origin would track this agent id and set it by default for all its users.