Vance, but in terms of "vibe" I'd rather have Rubio in '28. Miller's pretty awful.
Edit: it's difficult to say because Vance is in the foreground while Miller is in the background.
Vance annoys me because he is actually quite intelligent and he knows better. I read his autobiography (Hillbilly Elogy) when it first came out and I thought he had real potential. But, as far as I can tell, he decided to sell his soul in pursuit of Washington power once he realized Trump's sales pitch worked. Ironically, of course, the populist shtick is really just another way to gain power and money.
I'm not sure what to think of Miller. He seems to have a rather modest IQ and an innate inability to think beyond his rather narrow worldview. It's like he sees everything through sh*t colored glasses.
If I was forced to pick between two sh*t sandwiches, I'd say Vance at least has the potential to come around some day, whereas Miller will just keep swimming in his own sh*t forever.
And that's my huge opinion. Everyone is obviously free to disagree, I will not pretend to have any special insight or knowledge of either one.