Flew the A350 (900 & 1000) for 5 yr before coming to UAL. The -900 is approx 777-200 size, & the -1000 approx 777-300 size. Therefore both variants larger / better payload-range than the 787’s. So I guess it depends on the mission they have in mind. Maybe even the 777-9X if/when Boeing gets it’s act together 🫣