"Best" website - not really, it's well designed when it comes to corporate websites but it's not really easy to use, too much content crammed on the page (one of the many reasons MSN/Yahoo were crushed by Google).
"Most visited website" - it's not even in the Top100, it's somewhere on the bottom of the Top 1000 sites since they started a campaign some time last year.
"Most translated website" - The only reference I can find to that is within their own publications which they published as a 'source' on Wikipedia and from what I can see, the way they're "boosting" that number is by including sign language translations and the translations of their publications (the entire website isn't necessarily translated, they just have material in various languages). Sign language isn't really a 'written' language and they even include local dialects of Sign Languages which is a bit dishonest to say the least, those people understand their proper written languages. If you go by that metric, I would say YouTube/Office365 is the most translated website because it has videos and documents, both spoken and sign language in pretty much every language including Klingon. For actually fully translated websites, I'd think you'd be looking at one of the many UN websites (Office for Human Rights perhaps), Wikipedia (290+ languages) etc.
A bit tongue-in-cheek, but the most "translated" website in JW accounting would be this one: http://unicode.org/charts/
The number of unique "written", living languages in the world is estimated to be around 300, the JW website is translated in more than 800 of them...