Assuming that you still got amenities for your stay, I would probably stay at Hyatt's because I like the style there better as well as the free breakfast.

The problem is that Hyatts often break the budget, so I go with SPG as a 2nd choice with their decent promos. The upgrade potential is huge, so if I was a higher end property I might still choose SPG because Hyatt's often won't give you the free suite.

I would never ever EVER stay at a Marriott though - I really hate their boring rooms.