Any strong leader would've improved situation in Germany about the time Hitler came to power. In fact, that's why he got elected at all. The situation was grim, and he promised improvement, and definitely had the spine to follow through on that. Hitler managed some improvement, but that wasn't the hard part. But in the long run, he was just a politician, not a manager and definitely not a general. And he wasn't intelligent enough not to try to do either, which ruined Germany in the long run and cost him the war.
Stalin was extremely reasonable by your definition. He brought Russia to a new level (superpower!), he managed to kill all his political dissidents and survive all of it, etc.
Stalin's success wasn't his own doing. Indeed, what he actually managed to do was to bring Russia to the brink of defeat by executing experienced generals. Sure, he did kill off/send to gulags
all the dissidents, but they unfortunately included (from his POV) his generals, a whole lot of his staff, and finally his doctor (with fatal consequences). Stalin was downright crazy and very paranoid, the reason Russia became a superpower at his time was Lenin's groundwork, Zukhov's victories and Hitler's technology. He did a lot to secure his own position, but if they did have someone competent at the time, history could've turned out very differently.
It's hard isn't it, this responsibility thing? Yes, democracies are only as good as the people in them. But such is the power of responsibility. Life is hard and that's just the way it is. Reality does not get better if you just outsource all your managerial problems to a "benevolent dictator" who is sufficiently intelligent to guide all of the stupid rabble to more glorious days. As history proves again and again, it might be good for a while and then it decays rather quickly and nastily.
Unfortunately, what I have seen is that "the people" just can't be trusted with that kind of responsibility. Maybe in more developed countries it's different, but here, they'll steal what they can, lie and embarrass themselves, not matter if in position of power or not. I wouldn't trust the majority of people I've met with watching over a sandbox, much less the whole country. Now, I've also knew some that I would trust with my life, and with much more than just a country. I suppose if one of them ended up in power, and didn't had to deal with all the buffons populating our government, then the country would probably be in for some good times (assuming those managerial abilities scale well). But stupid people are much more numerous than intelligent ones, and moreover, it's usually the stupid ones who want power really badly. The reality, in fact, can very well get better with an intelligent, benevolent dictator at the helm. The only problem is finding a reliable source of such dictators, since they aren't easy to come by. In a democracy, degeneration might be slow in cases it's bad, but so's progress when you get a good government, meaning you're pretty much doomed to be stuck where you are. Though since getting a bad government is generally more likely than good, this is indeed a valid argument for democracy.
Putin squandered everything. He had a real shot at doubling Russia's GDP (his own professed goal!) and even with the oil price basically skyrocketing to today's levels, he didn't even manage to go anywhere near that. It's a massive failure, russian youngsters are fleeing the country, he has completely lost the demographic war, and he's just trying to compensate for his domestic failures by creating outside threats and scapegoating all the problems unto "others", like the gays, the jews, the oligarchs, and why not, NATO, Israel, etc., etc. And if by doing so he pockets a lot of weapons' money, so much for the better.
Yeah, Putin did screw the gas deal up, I suppose a lot of it came out of using it as a political pressure tool as well as the income source. This is definitely a place where his politics failed, other countries are not very interested in relying on Russian gas, because Russia has a nasty habit of threatening to cut if off whenever it doesn't like something. Putin's aggression is a mixed bag here. On one hand, it did get him a part of Georgia he wanted, among other things. On the other, he's alienating his neighbors, which definitely isn't too good for the economy.
