Please see the respective master threads for full reviews with photos, but out of the two Bonvoy properties I tried in Berlin, I think I would choose to return to the Westin over the Marriott as the bed is more plush and they seem more willing to upgrade to suites. I did like that the Marriott had a club for evening options, but as I didn't love the evening options and I preferred the Westin's restaurant breakfast offering over the club breakfast at the Marriott, the Westin, at least for me, is an easy choice.

The Marriott does have better shower pressure, though.