It's pretty clear Trump has the lowest margin of approval ratings at 15 points difference to Biden's 21. However, Dubya has the honor of lowest approval rating amongst living presidents.
This is basically why Democratic politicians are less popular than Republican ones. A Republican president will be liked by 90%+ of his party and nearly no Democrats. A Democratic president is liked by half of his party and called a genocide supporter by the other half, and supported by nearly no Republicans.
Yeah, but half of the country has abused spouse syndrome with trump. While the nicest things most progressive people have to say about Biden is that he wasn't Trump.