I find "ought to" a little more mild though. "Should" is more of an imperative, "ought to," to me, contains a slight implication that you won't, even though it would be better if you did.
I disagree, Soz. How can 'ought to' contain any implication that "you" won't, when the person receiving the advice [inherent in should/ought to] is different from the person offering the advice.
A: [to B] You ought to/should go see [movie name]. It's really good.
At this point, A has no idea how the advice will be received by B.
should/ought can both be weakened or strengthened - probably, likely definitely should/ought to ... .