Both Marriott and Renaissance are dated, Marriott might be slightly more luxurious and has the central location in its favor. But I still prefer the Renaissance over the Marriott because of its location close to the European quarter and the „locals places“ like Place Jourdan, Parc Leopold…
The best rooms won‘t be at either of these properties, I feel like the Courtyard Brussels EU has the nicest Marriott rooms in town. Can‘t wait for the new Autograph Collection to open next year and I‘d really love to see the other properties being renovated.