I'm coming off the back of GGL and currently GS due to a change in work travel contract. Overall I'm really satisfied with the United offering, downside for me is minor convenience (T5 vs T2), and being UK based only being able to use PlusPoints upgrades for US destinations versus more options/upgrades with the BA scheme. I find the hard product and service comparable.

The United tech is worlds apart. I recently had a flight cancelled at the gate. Approx. a minute before they announced I had a notification. From the app I could 1) select from a choice of nearby hotels and confirm reservation, 2) click to order a paid for Lyft or Uber from airport to selected hotel (and return), 3) display 2x food/credit card vouchers I could scan using apple pay, 4) select what option I wanted for adjusted flight. Honestly one of the smoothest digital experiences I've had anywhere, for what is otherwise a PITA situation.