Here's my take:

Location:
Marriott: Very good
Courtyard: Good
The Marriott is 5-10 (walking) minutes closer to tourist attractions, the river, and public transport. For nightlife and restaurants, the Courtyard is located a bit better.

Hotel facilities:
Marriott: Good
Courtyard: OK
The Marriott has a good restaurant, an OK gym, a nice executive lounge, and very good breakfast.
The Courtyard has a nice gym and a small bistro. Also: You can charge your Tesla there.

Rooms:
Marriott: Very good
Courtyard: Good
Marriott has bigger rooms, minibar, very comfortable beds, and nice bathrooms. WiFi can be bad, though.
Courtyard has good WiFi and very modern rooms with a nice bed.

Upgrades:
Marriott: As a gold, I get very large rooms and lounge access.
Courtyard: I usually get a larger room with plenty of space.

Conclusion:
The Courtyard is only 2 years old - so a lot more modern compared to the 10 year old Marriott. If modern rooms, good WiFi and AC are important, go for the Courtyard.
Otherwise, the Marriott has more to offer in most categories. I especially like the lounge and the close proximity to the river.

Now, is it worth 75% more points?
Personally, I have to say no. I really like the lounge and the location - but just for that, the premium in points is just too high.
Depending on your priorities your choice might be different, of course.