What countries would be the easiest to take over?

If you're a military general or police commander with enough backing in your forces in a country with a poor, unarmed population, that would present a fairly easy target for takeover. Some of the countries in central Africa would fit that mold. A politician with such asperations would need to be good friends with the police or the military.

Even in that scenario, you would need some public support. When people who take over countries are so bad that the population is willing to die to remove them, they don't last very long. To avoid that, they usually reward people capable of creating such an uprising with special treatment at the expense of the poor and weak.

Or... you could run for public office anywhere else and promise everybody a free ride. :-)