There are several threads on this already. However, I would say that you should play whatever you think will be most fun for you at 80.

Both pallies and bears are effective Tank+4xShaman classes. I've run both. I personally enjoy the flexibility in being able to go Boomkin+4xShammy as well.

Bears can also be "1 button tanks". You can glyph for maul and generate a lot of aggro using a very simple Maul+Swipe macro.