Big city
Not fussed about the weather, but it would be nice to have warm, dry summers.
Good international transport links
Museums and art galleries
Restaurants, bars and gig venues
Good public transport links to the countryside and to the coast
Good public transport links within the city
Good cycle infrastructure
Good selection of jobs in my sector
(related: Lots of high quality architecture being built)
Affordable place to live within a cycle ride of work/the city
Able to afford a house with a small-ish garden
Local neighbourhood shops and restaurants and places to drink and parks
Country with good healthcare provision, social welfare, good worker’s rights, moving towards a standard four-day week
London ticks most of those for me, and is definitely the only place in the UK that comes close, personally.