The Tube is direct, easy, cheap and uncomfortable. My neck normally starts complaining by Hammersmith.
The HEX is ridiculously overpriced, and changing at Paddington is a bit annoying (you need to use the "Hammersmith & City" Tube station, not the main one, although better out of the rush hour, and they've now at least installed lifts at the Tube station. You'll save a little time, and it breaks the journey up, but it will cost much more. Of course, you can also switch to Uber at Paddington - they pick up on the street just to the left of the ramp up out of the station.
A slightly unorthodox option (that I often use) is to change at Hammersmith. It costs the same as the direct Tube, but breaks the journey up, allows you to grab a sandwich and a coffee on the way, and means you join a quieter, larger, air-conditioned train (that is above ground for part of its journey). The complication is that you need to change stations in Hammersmith (exit via a shopping mall, cross two pedestrian crossings) and not always the simplest for the uninitiated.
But yes, the Piccadilly Line is easy.