If we killed hitler we would have more competent nazi and possibly still third reich over here but no Poland and I am selfish I wanna exist ya know
Best person would be trump as it is recent enough to not suddenly cease to exist due to various butterfly effects, still pretty risky though. All of people that died by accidents between trump election and today would be from different, new set. You can calculate probability even based on average yearly accidents.
God I shudder to think what if u killed Julius Caesar. We would be like unrecognisable due to all branching out possibilities over the years. Real quantum parallel worlds shit