If you go by approval ratings, George "Dubya" Bush was the worst president in modern American history (since 1960). During his watch, we had the 9/11 terror attack where 2,977 people died, the 2001 recession, 4,400 Americans dying in the unnecessary war on Iraq, the grossly incompetent response to Hurricane Katrina / New Orleans floods where 1,392 people died, and the Great Recession where over 30 million people lost their jobs and 6 million people lost their homes to foreclosure.

Dubya's approval fell to 22% in 2008, which is about half of what Biden's approval rating is today.

en.wikipedia.org - Public image of George W

Second worst president in modern American history was Donald Trump, who left office with an approval rating of 34%, which is lower than Biden's current 39% approval rating. 40% of the 471,000 American deaths due to Covid could have been avoided if Trump had handled the crisis better. President Trump publicly dismissed its threat (despite privately acknowledging it), discouraged action as infection spread, and eschewed international cooperation.

businessinsider.com - Analysis trump covid response percent US deaths avoidable

Trump is also the worst jobs president in history with job losses totaling 4 million under his watch.