I've been to the Four Seasons and the Sofitel before and enjoyed them both.

Four Seasons definitely more high end and is attached to the Venetian and possibly the largest DFS I've ever been into.

Sofitel is located in the old part of town and close to all the historic sights, not super luxurious but definitely a comfortable stay and probably would get my vote slightly over the FS (I'm more into the history of Macau than the gambling)

Staying at the Mandarin next month so will provide an update then.