I see so many users mutter not nice things about the Ribbon, yet very few bother to take 10 minutes per Office application to customize their Quick Access Toolbar. Put your most commonly used commands there. This alone will substantially boost productivity in every Office application.

And, since it looks like some folks are voting for their favorite word processor... My all time favorite was AmiPro - before IBM bought it and destroyed its intuitive interface and renamed it (Lotus) Word Pro.