Neither of them will make good presidents. Kamala Harris will be similar to Joe Biden. I doubt she will make any decisions on her own.

Donald Trump would have to figure out how he's going to please the Establishment while not antagonising his supporters. It's a difficult balance if he's president.

There is also the possibility of some major events that could change everything. For example, during the final year of Trump's first term as president, there was Covid-19.