You're asking for a choice between Frank Underwood (Centrist with only one care in the world) or a left-wing Francis Urquhart (Lightly ideologically convicted, but still not above being ruthless)
Now if Nixon were up against an Ideological Convicted Centrist Urquhart or Reagan (who pretty much IS Urquhart, except coming off as an idiot with a soothing voice rather than a subtle manipulator), Nixon would be the answer... an opportunistic Centrist will once in a while allow the Government to do what it needs to do.
However, since Hillary is a left-winger to some extent, this flips the dynamic. In this case the Opportunist Centrist would be more likely to go away from government regulation.
Nixon knew when to quit, so he gets my vote.
Not following his "last press conference" promise in 1962 says otherwise.
He resigned the Presidency rather than go through the full process of impeachment and therefore maintained respect for the office of the Presidency.
Oh please, the full process would've probably meant prison without any hope of pardon.
And once again, that doesn't negate how he decided to go against Pat Brown after losing to JFK, or how after that he ran in '68 when pretty much anyone not named William Jennings Bryan would've given up after the loses.
Also, it was literally in his resignation speech about how it "goes against" every bone in his body to give in....even with approval ratings only topped by Dubya.
How you managed to construe this as "he knew when to quit" while implying Hillary doesn't because "muh decided to run again even with a few partisans being haters over carelessness regarding cyber-security and losing to Obama in '08"...that's beyond me.
By the same logic, Al Gore should've quit after '88, "St." Ronnie should've never come back after '76, Humphrey never should've even bothered after JFK whooped him in '60 and LBJ was in the pits.
Therefore the argument holds no water at all.
When literally all sides of the aisle are out for blood against her [and no #BernieOrBust don't count]...that'll be different.