I'd have to toss a coin to choose between my two favourite moments from that trainwreck:
Trump pronouncing "Antifa", slavishly followed by Biden, like it was an island in the West Indies (AnTEEfah).
Biden shoehorning in a reference to Trump's alleged reference to WW1 dead as "losers" by pretending he was misremembering Trump's attacks on his corrupt druggie son Hunter as being attacks on his brave veteran son Beau: that's a courageous stratagem for a guy the GOPers are keen to paint as senile.