[member="Tirdarius"]
Funny you should bring up rulership. Many Sith are competent leaders, because while they are selfish (Sith philosophy, separated from the Dark side, still promotes a high level of self-interest), they are also pragmatic. The politician, the trickster, the scientist, and even some versions of the Monster can produce this effect, as a shrewd, capable leader need not be a moral one. These types are the Lex Luthors and Kingpins (I like comics) of the Dark Side, the people who can see the long game, and who play. Palpatine, Cadus, and many others are prone to this somewhat Machiavellan approach to ruling a nation.
Jedi have a different problem with leadership, which is detachment. As most Jedi philosophies (unlike Sith, there's not a lot of unity in overall intent) emphasize emotional and personal detachment, as well as separation from material concerns in favor of the spirituality of the force, leads to a certain weird relationship with Jedi and power. Those Jedi that do actually exert the will to rule often either forcibly develop a very calculated approach to ethics, including the willingness to sacrifice many people for the needs of many more, or to try and build some strange idealistic form of governance, which often falls apart rather heavily from the tampering of outside forces.
Now, don't take this as meaning that Jedi can't rule, or haven't ruled successfully. They have. However, ruling in a governmental capacity comes more naturally to Sith than to Jedi, purely because more Sith are trained to take and wield power, while Jedi are often trained to avoid the sort of permanent/long-term attachment normally ascribed to involvement in political rule of a planet or nation. This leads to truly fascinating issues.