The Triumph, because it’s mine. ;-)

Honestly, horses for course.
The Triumph revs like a sports bike, you can keep it on the boil and really hammer corners in a manner that’s quite impressive for something that is effectively a large tourer with hard luggage etc.
The BMW is all torque, with it’s lower revving boxer making for incredibly tractible power, especially at low speeds. It’s also got a lower centre of gravity, which just makes handling it so much nicer.

If I was purchasing again, I’d probably go the BMW and sacrifice the performance for servicability.