PAVLOV, interesting list of leaders and discussion! But I agree only about Nicholas II in the case of unprepared and unfit rulership. I agree with previous post, that all these men, you've mentioned (excluding Mr Lenin and Stalin) were elected on free elections in the free/liberal and what's more important democratic countries, where educated by Lincoln and Adam Smith population, commonly elect their Presidents/Pr. Ministers! So, it will be better to say that not Mr Roosevelt or Churchill and others were unprepared or unfit to rule, but American/British population and political elites at that time were unable to elect someone another "prepared" and with brains. Btw, I think that today's sad example with intelligent and unprepared man (without names and countries!) is also shows us "left" and sad utopian mood in this free and great country. God bless the next elections!
As to the Stalin, I must say, that he was unprepared/unfit so much, that he ruled the country for about 30 years and even today Russians (those who live in Russia) are studying History by his own made/falsified history textbooks, thinking as he commonly thought and moreover he is universal figure for ordinary people (who didn't studied other non-Stalin History): biggest communist, biggest Russian nationalist, biggest monarchist, including all of the Romanovs and so on. All these qualities are in one man! This would be an impossible dream for Hitler, whose ideas are officially banned in the most modern countries, while communism and other "left" utopian ideas, which permanently lead to human blood as an any ultra-right, are not officially banned today in Europe. So, you can just go out to the street in Mr Stalin or USSR red shirt, and people around who don't know about Gulag would be saying you all the way: "Cool red colours!". Concluding, man doesn't exist already for about 50 years, but his ideas fully passed (with the help of penultimate Russian president) to the millions of Russians and even some Europeans! (happily they are in minority). I think that in that case term "unfit" is very unsuitable. Of course he was an evil or great evil, but not the man, who was unfit or even unprepared for the rulership. Just sober opinion.