Since this is Atlas, Pence will likely win this pretty easily, but among registered Republicans outside of Atlas, I think we know who's actually more popular.
That's only because Fox News hasn't been promoting Pence's brand the way they have been doing for Trump and did for Bush. Once he ascends to the Oval Office, and the Fox News Channel to start cranking its gears, wait for Trump's supporters to fall in line for him. Especially if he is billed as their last best chance to keep the White House in Republican hands.
Total misunderstanding of the conservative mindset. Guys like McCain, Romney, Pence could never win over the hearts and minds of Republicans one-on-one with Trump. Those are begrudging votes, not inspired ones. They're not fighters. Trump is a fighter.