Brent Jesse's Site has some useful impressions of the NOS versions of those tubes, as do other forum sites like AudioAsylum. The link is for EL84's and you can find others at the top of that page. It will depend entirely on the equipment you use the tubes in, and your own personal preferences as to which sounds best. As a broad generalization, certainly the Mullards are commanding the most money and are known for midrange fluidity, natural extension and balance, FWIW. I've found the Russian NOS Reflektor 6n14n-EB (similar to the more rugged Sovtek "M" version) sound rather analytical in comparison to what I'd expect from Mullard...perhaps more SS in that way. I would try those over the standard Russian EL84's regardless. Also check out 7189A variants from the U.S. It would certainly be a cheap experiment to just try the out as they are not nearly as expensive as the Mullard NOS. I recall liking the Svet EL34's but could never afford a quad of Mullards to compare, and that was a long time ago too. 1-10 ratings are useless IMO - what I like is not necessarily going to be what you like, and I also do not have the experience of running those tubes with the same gear in the same system. Tube prices in the NOS end are largely determined by supply and demand, with rare examples commanding big bucks, while not necessarily outperforming less expensive alternatives. Not saying that's the case with the Mullards you are considering...some demand is generated actually because the tube is truly oustanding. The Mullard route would be an expensive and risky experiment though - If I went that route myself, I would buy from a reputable seller.
Good luck.
Good luck.