Personally I believe, as with most things in life, you need to find a good balance between the two, not all people should be treated the same obviously.
You need an ego, being too soft will get you nowhere, some people need to feel you are in control or they'll walk all over you, while other people can be treated with more gentleness.
Nothing in the world is either black or white, it's always black, white and everything in-between.
I see no reason to chose either one of those paths.