"For example whose side would would you have taken when Stalin and Russia where fighting each other?"
"How do you pick between genocidal dictators?"
Go after the one with the smallest army. Better yet, mind your own business unless you and yours are the intended genocidees.
"or to shoot a dictator to stop a genocide."
That would be an easy question to answer if you only had to shoot the dictator. Trouble is, they usually have an army you have to deal with first, and then lots and lots of people get shot, including a bunch of your own. That's a problem we generally seem to have trouble figuring out, but at least we had the sense not to mess with Good Ol' Joe, who had an army of about 10 million at the end of WW II. And he had the sense not to mess with us. All in all, a decidedly moral decision on both sides, given the likely outcome.
"Principled people have taken variations of both positions but few hold position with complete consistency."
Probably because a lot of situations like the ones you describe are extremely complex and involve a lot of contradictory moral principles. In general, I would say it is better to avoid killing in all but the most extreme situations, but I doubt I could apply that principle in all cases.
"How does this connect to bears, I lost track."
From the bear's perspective, if we're arguing amongst ourselves, we're not shooting at him. Which is probably why I'm jerking your chain a little. ;0)