Where have the most strongest and deadlist tornadoes occurred?

See the links below. The first is a list of confirmed F5 and EF5 tornadoes in the United States in the years 1950-present. In addition to these tornadoes there was also an F5 tornado in Elie, Manitoba (Canada) on June 22, 2007. Most of the tornadoes on the other list were also probably F5's including the Tri-State tornado.

The second link is a list of the 25 deadliest tornadoes in U.S. history, most of which would also count as the deadliest in world history. The deadliest tornado ever recorded anywhere was the Daulatpur-Salturia (Bangladesh) tornado of April 26, 1989 with over 1300 deaths.