I'd say Hilton.

Yes, there are more PC properties, but generally Hilton's are within easily commutable distances to wherever.

However, with BMI Diamond Club and Hilton Hhonors you can double dip your way to some serious miles and points.

Your 40 weeks of M-T would get 120k miles, nearly enough for two UK-US round trips in Business class (four trips if using cash + miles). Book through BMI and you'll get even more miles.

Similarly you'll be points rich with Hilton to cover your leisure travel stays.