Good place to buy watches in Paris/london?

Anybody from London or Paris?

Will be traveling to both cities next month. Any good watch shops for second-hand/used with good prices? Shops that sell vintages would be greatly appreciated as well.

Maunder watches, Burlington Arcade, Piccadilly London.
Always welcoming, knowledgable and often some lovely vintage watches. Not necessarily the cheapest though

Don’t think you’ll find london prices very attractive.

I see, London might be more tough then. Anyone knows anything in Paris or Amsterdam?

The Arcades around Mayfair are great for window shopping as others have mentioned but it's mainly high end dealers. Clerkenwell was traditionally the watch hotbed of London especially for repairs and parts suppliers and there and there are indeed a few watch related businesses still there. There is also the Antique Watch Co who have a shop there usually with some interesting watches in the window. They have a website too. I saw somebody else mention Kibble Watches. Their showroom is in Farringdon which is right by Clerkenwell but I believe its open by appointment only.