From King’s Cross St Pancras, take the Piccadilly line directly; if crowded

https://emilianoybbe285.iamarrows.com/heathrow-express-vs-elizabeth-line-fastest-way-to-heathrow-from-central-london-1

From King’s Cross St Pancras, take the Piccadilly line directly; if crowded, consider one stop on the Circle/Hammersmith line to an easier interchange at Paddington.