We had Pence the first time around. He was definitely scary. He wore his religion on his sleeve, and really brought nothing to the table. He would never have been a good successor had Trump won in 2020. I obviously don't know if it's true, but I seriously doubt Trump ever asked Pence for advice, or listened to Pence if he offered advice. I doubt Pence would have been able to handle being POTUS had Trump been unable to continue.
JD Vance is almost everything Pence wasn't. He's personable, quick on his feet, smart, has great experience as a soldier and businessman, and is articulate. He doesn't wear his faith on his sleeve. He has gravitas. It remains to be seen how he will deal with Trump's policies he might not agree with, but it's likely Vance will have Trump's ear on financial and defense policies and issues. We'll see I guess.
Bottom line is I think Vance is an upgrade. Again, we'll see, but the last 2 VP's certainly would have been disasters if they had to take over as POTUS.