>>202I'm gonna say that Palpatine ended the Jedi reign. Vader did kill a lot of Jedi. Though most of them were under 12.
And I'm gonna give the 'ending the rule of two' to Luke. Yes Vader stabbed Palpatine in the back while he was distracted with Luke, but he probably wouldn't have done any of that had Luke not convinced him to.
Vader might be really strong in the force and in general, but he was pretty crap as a Sith lord. If Luke never showed up, Palpatine would probably have killed and replaced Vader eventually.