I have said many times that Mitsouko is one of the few fragrances where I like every single version of it that I have smelled (well, except for that flanker Guerlain did, the Fleur one...which I have not smelled yet). The EdC, EdT, EdP and extrait (new and vintage) are all splendid. NOTE: Many Mitsouko that is vintage has turned slightly in the top notes so you have to be careful when buying on eBay.
If I had to pick one, it would be vintage Extrait. It has a green, medicinal, sharp intensity to it that sort of intensifies for quite a while before the peach/moss rushes in. For a few minutes it doesn't smell like a chypre or like itself...but some sort of poisonous, spiky, harsh smell. Which I love.