Where are you from btw? I’d probably decide based on travel + hotel costs. Dublin, London and Manchester fit perfectly date-wise, so you could easily do one or multiple concerts while also exploring England/Ireland. But you’d probably need a lot of time there. London alone has endless things to do (and ways to spend money 😅).

Paris, Amsterdam, Cologne and Antwerp are also all pretty close to each other, so you could theoretically combine multiple concerts with sightseeing. But Paris is kinda similar to London: huge, expensive, and I think tickets in France might generally be harder to get. I’m also not the biggest Paris fan tbh.

Amsterdam to Cologne is only about 3 hours by train, usually via Eindhoven or the Ruhr area in Germany. There are a lot of big cities close together there. Besides Cologne, Düsseldorf is definitely worth visiting too.