I'm in my Conrad HK (harbor view) room right now. I'd agree that the Conrad is a notch below the Grand Hyatt HK. Conrad's location is better, attached to Pacific Place, with quicker & easier access to MTR and all the other local transport options (buses, tram, etc.)

Rooms are comparable. GH rooms are small, and its once innovatively-minimalist rooms are now commonplace and banal. Conrad's pool and gym are small and worse than GH.

GH's grand club lounge is really nice, with great food selection at both breakfast and happy hour. Not know about Conrad, as I don't have access to their club.

If you have access to GH's grand club, go for GH. Otherwise, they're comparable.