As others have pointed out, there is no such thing as a humanitarian dictator. If one exists I want someone to mention hir by name please.
And don't say Fedal Castro. That guy kills political opponents, limits freedom of speech and censors the media up the ass, and is a lying tool: just like every other communistic-style dictator.
Now, however, there are plenty of examples of weak democratic leaders that can be tossed around, and heaven forbid if your parimentry democracy is in minority governments where all of the parties don't want to deal with the others (as you are forced to in a minority government to do so if you want parament to last more then a year). Again, as many have mentioned, a weak democratic leader can be removed from power within four-five years, or sooner if there is a vote of no confidence or criminal activity.
Now, the sad reality is that shit gets done in a dictatorship, and it gets done fast. Usually, in most democratic nations, there is something known as War-Time Measures, or Martial Law, where the leader gains dictator powers for a certain period of time - normally during a war as the name War-Time Measures implies. In Canada, this has been used four times
1) During World War I
2) During World War II
3) During the October Crisis
4) During the last G20 summit to take place in Toronto, ON.
Now, thankfully Canada at the moment isn't under War-Time Measures, in fact, the 3rd example only lasted a month and the 4th example only lasted a weekend. Still, it address the ineffectiveness of democracies during a time of war. Of all the strengths of democracy, speed was always its greatest weakness.
Though, I should quickly note that communism is a economic structure, not a government structure.
Now, in any given place, the people are only willing to put up with a dictator if their basic needs are being met. You can bet your ass that once the dictator gets too cruel and greedy, and the people have nothing to lose a rebellion will insight.