My preference is Courtyard. Of course, I've never stayed at a Fairfield Inn.

If you're interested in how new or newly renovated a property may be, Marriott's web site is an excellent source of that information. You can click on the "Room Details" and find out when the hotel was built and what year the rooms were renovated (if they have been). For example, the Courtyard San Diego Downtown was built in 1999 and the rooms were renovated in 2007.