Depends. If you use power attacks/shield bash a lot, go something like 2:3. If you're ok dishing damage but are struggling to take it, try a 3:2. Depends on personal preference.
Probably the best advise. I've been doing about 3:2.
Basically, each time I level I think back to what seemed to be most in short supply over the last level and I bump it although I make sure both go up regularly. I usually end up needing a bit more health then I do stamina. Besides, if I run out of stamina I can just lay off the power attacks and kill it almost as fast. If I run out of health I have to load a save.
For me I just assume there's no way I'm going to be able to power attack my way through every fight. I usually save them for key points in the fight. Like things which are really laying down the hurt on me. Magic users are especially likely to get one of my signature one-shot kill power attacks.