ToolStrip with MenuStrip or RibbonBar?
Why Ribbon Bar? It takes a lot of space. Menus and ToolStrips have a more compact look and they are very intuitive.
It boils down to what you're trying to navigate and how complex do you want the Navigation to work.
I prefer to use simple existing applications to base my programs.
Thus for the most part I use either the MenuStrip + X ToolStrips or just a simple ToolStrip if a menu is more involved than is required to get a task done.
But I would have to guess that many people like the Ribbon Bar since it combines the functionality of both Menu and ToolStrips into one control.
It combines both of the controls. It also have a TabPages navigation, contextual tabs, etc. However the RibbonBar is a very complex control and when you open a new document in for example Word2007 the half of the screen you see a Ribbon Bar. It is not cool. When you have toolStrips you can layout them to Top, Bottom, Left, Right and have more control of the UI look. We can also hide the toolstrips which we do not want to see and they no longer take any screen space.
Ribbons look more modern, and will help to give you application a modern and current look.
As for usability, I've preferred the experience, as long as you are unfamiliar with the app.
For apps where you are used to a menubar, it's a difficult change, but for new apps or new users it's a good improvement.
I agree with you Rich. It looks modern, but why it looks modern? Doesn't it look modern because Microsoft have said that?