Dolos
Lets say that Padme turned evil too for whatever reason, allowing this to happen?
First, we all know how powerful he was. He was able to double his powers between like his 5th battle with Dooku in the Clone Wars TV series and final battle with Dooku in Episode 3 - that's a doubling of power made in less than a year. We also know that he was able to kill Dooku in moments whereas it took Yoda a very long time to get the upper-hand in both their encounters by using the Zone.
Second, we know he had very limited access to the Jedi databanks because of the Council's fear of his abilities. But as Emperor, we he'd have access not only to all Jedi and Sith literature contained in the Temple on Courascant; but all knowledge every. Here and here Gideon explained how in depth that knowledge is - furthermore it is safe to say that Anakin would try and become immortal using Plagueis' midi-chlorian manipulation. As the Chosen One, on Mortis, it is demonstrated that Anakin was not just able to quickly advance his strength in the Force, but that he was also the most gifted sorcerer of all, able to wield the full energies of Mortis when on the nexus by virtue of being the Chosen One. He could perhaps obtain immortality far easier than Plalgueis.
Lastly, we know that as Emperor most of Vader's battles are ahead of him, so he has 20+ more years of combat experience to gain, most likely as an immortal Sith Lord stronger than all before him.
First, we all know how powerful he was. He was able to double his powers between like his 5th battle with Dooku in the Clone Wars TV series and final battle with Dooku in Episode 3 - that's a doubling of power made in less than a year. We also know that he was able to kill Dooku in moments whereas it took Yoda a very long time to get the upper-hand in both their encounters by using the Zone.
Second, we know he had very limited access to the Jedi databanks because of the Council's fear of his abilities. But as Emperor, we he'd have access not only to all Jedi and Sith literature contained in the Temple on Courascant; but all knowledge every. Here and here Gideon explained how in depth that knowledge is - furthermore it is safe to say that Anakin would try and become immortal using Plagueis' midi-chlorian manipulation. As the Chosen One, on Mortis, it is demonstrated that Anakin was not just able to quickly advance his strength in the Force, but that he was also the most gifted sorcerer of all, able to wield the full energies of Mortis when on the nexus by virtue of being the Chosen One. He could perhaps obtain immortality far easier than Plalgueis.
Lastly, we know that as Emperor most of Vader's battles are ahead of him, so he has 20+ more years of combat experience to gain, most likely as an immortal Sith Lord stronger than all before him.