This isn't to choose either, but rather a follow up question I'd ask of each person answering that poll: Name three (or more) things that your pick did better than the other that influenced your choice.
That is, if you chose Biden, name three things he did better than Trump has to date. The same goes if you picked Trump. The reason for that is if people are simply choosing on the basis of personal opinion, political party or position, and not on the basis of actual results--which is what "did a better job" means--then they aren't answering the question but rather just foisting an opinion based on nothing.