I'm really not sure either way. Trump will use the exact same strategy whether his opponent is Biden, Sanders, Warren, Buttigleg, Smiling Amy, Shaquille O'Neal, or Donald Duck:
1. Lie. Boast. State half-truths. Act cocky and confident.
2. Insult your opponent--as crudely and childishly as possible.
3. Misrepresent your opponent's position--as brazenly as possible.
4. Continually deflect the discussion away from the issues.
5. Attack, attack, attack. Put your opponent on the defensive so you don't have to defend yourself.
6. Lie some more.
Who would be best against this strategy? I honestly don't know. The only thing I do know is that the Biden and Smiling Amy approach would utterly fail. Trump's a balls-kicker and eye-gouger. You can't treat him--or any Republican, with the exception of Mitt Romney--as if he was going to act decently or play by the rules. He won't. He's a total asshole and a cheat to boot and acting as if he ever intends to be anything else is foolhardy. Biden and Amy think we can all "come together." Yeah, right--if we're all wielding baseball bats, maybe.
So maybe we should just go all in. Hit Trump and conservative dogma with a candidate and a philosophy that are diametrically opposed to them. One thing I would really want to know, anyway--just what percentage of the American people actually do want to see "radical" change (you know, radical, like electing a professional con man who is utterly unqualified for the job)? We might get a BIG surprise if Angry Grandpa, er, Bernie is the challenger.