Their margin of error is considerably lower than your average NHL team. They don't have an owner willing to spend money. Now that in itself doesn't automatically mean success (as the Glen Sather Rangers would've won multiple Cups in the non-Cap era) but it does make the job easier. As such, if I were a betting man, I'd bet on the Canucks (no GM is infallible; one is bound to make the odd mistake and having a green light to spend money mitigates this issue) over the Sens.
I don't know the ownership situations in Colorado & Carolina. Though the Canes have a strong/deep blueline, I agree.