It's probably down to context more than absolute taste, but the best croissants I ever remember having were from our local bakery when I lived in Amiens, in Northern France. It was just a little shop in a fairly run-down 70s shopping parade, but the 'pur beurre' croissants were out of this world. It really taste as if the centres were made of pure butter - you wouldn't even have considered putting something on it.

(They also did a wonderful millefeuille - when I think of what passes for millefeuille in the UK even now...)

Recently, the best I've had has been from a bakery in Nanterre-Ville, although their star attraction is the éclair aux pistaches. They did a wonderful piece montée for my godson's baptism, too.

In the UK, the best I've had has been at the Hotel du Vin chain. And the Pret almond ones are very moreish.

I agree that crisp outsides aren't good on a croissant - you should get nothing more than a fine, soft flake from the outside (and my favourite ones in France have been this way too). The best ones will not leave you wanting a topping.

I also agree that you can get some excellent ones in Japan - I have particularly good memories of the bakery on the bridge in Kyoto Station (I'll be staying in the Granvia in a few days, so I'll find out if I'm right).