Preference in Dubai: the JW Marriott or the JW Marriott Marquis?
Depends on which part of the city you need to be in----traffic can be aweful, so look at the maps, and decide re: if you need to get to work somewhere close.
Have been at the JW (not Marquis) many times, and again next month. Central location, very near airport, excellent exec lounge, excellent gym, etc.
Make sure to confirm non-smoking rooms anywhere in the Mid East---confirm, not request.