None of this matters much to me since I'm often staying someplace close to Paddington and/or Mayfair. If I'm not staying there, I'm off to Canary Wharf and it's a taxi ride no matter what.
If you're fine with lugging baggage up and down the tube stairwells, then fine by you, but I prefer the Express for any number of reasons and time of travel/distance traveled isn't the sole determinant of my choice.
If you're staying near Paddington then sure, it makes sense. But for going to Canary Wharf the tube option is pretty nice - just change at Green Park (step-free since the rebuild) to the Jubilee line.
If you're fine with lugging baggage up and down the tube stairwells, then fine by you, but I prefer the Express for any number of reasons and time of travel/distance traveled isn't the sole determinant of my choice.