I wouldn't call Palpatine's election legitimate. Well, maybe his election to Supreme Chancellor, but all the votes on adding Emergency Powers and such most definitely were not legit.
He clearly used the Dark Side to influence those votes, or at least make them come up(although blaming Jar-jar is certainly the easy way out) at a time when they'd definitely pass.
I'm of the opinion that the Rebellion was doing the right thing for the wrong reasons.
Opposing the Empire was the right thing, fighting to restore the Republic was the wrong reason.
Creating an entirely new system of government from either the Empire or Republic would have been a better route. People ostensibly made Palpatine Emperor because the Republic was a failed system(a true statement), you could co-opt that sentiment by saying "yes, the Republic had failed. But the Empire is worse. So follow us and we'll give you a third option better than either."

