The bear is normally the best tank. For it to be effectful you need to place points in dire wolf, and maybe some in oak sage. +skills helps a lot. A well made grizzly can have thousands in life, and deliver good damage as well.
The dire wolves, as I see it, are only handy when a lot of bad guy's comes running at you from different directions. In such a situation use the dire wolfs.
Letherian