I would choose Voco for the following reasons:

1. More modern property - rooms are very stylish
2. Spectacular views, though that might depend on getting the right room, but as Diamond you stand a better chance
3. The roof top bar Bar Albert is a great venue with spectacular views

Only negatives for me regarding the Voco are that the lobby is small and that breakfast was kind of average. I remember the CP set up being better. Check out time at Voco is 10am and they only gave me a late check out till 11am. At the CP there is a lot of construction right now in front of the hotel due to the ongoing construction of the light railway project.