Stayed last at both D Cube and Westin a month ago. This is my take:
D Cube is a distance away from the city centre but not a problem for me to travel on a daily basis.
Westin is near to almost everything but is busy and quite crowded.
In terms of rooms (suites) I much preferred D Cube - much better furnished simply because it is much newer.
Service standards for both hotels are very good, Westin slightly more efficient while D Cube is slightly warmer.