I don't have strong favorites other than my home nation on this world cup and in rugby in general. But more than others, I support Ireland, Wales and Scotland. These nations, especially Ireland and Scotland, remind me of my own country very much. We have many traits of character that are similar, many aspects of history that is very much like our own and so on...
But that doesn't mean I don't even supports other teams. In each game I can have sympathy to any rugby nation. Depends how they play that particular game and other aspects.
The only team I will NEVER ever support, no matter against who it is playing, is Russia.
No offense to Russian lovers...