I agree that it should be about running the ship of state, who would be the best president and be able to do the most for the people. But it isn't. For roughly 2/3rds of all Americans it all about the letter behind the name. For 90% of those who affiliate or identify with both major parties, it's the R and or the D that decides their vote, not the best or worst candidate.
For the other third, call them independents, swing voters, the non-affiliated, whatever. They're all over the place as to the reason/s they vote the way they do. How they perceive the two candidates, their like or dislike of the candidates usually comes to the fore. Sometimes it's the one with the best slogan, the one who looks the most presidential, who their friends, family vote for, their stances on an issue or two, there's a lot of one issue voters out there. It's impossible to state all the reasons or to even quantify them.
I would say very few take into consideration who would be best at running the government. Then again among those who decide their vote on the letter behind the name actually think their candidate will be the best. Each individual views the two parties differently along with their candidates. It all boils down to how each individual views the candidates, their perception of the candidates, whether or not they did something to make folks angry or how they view the job they have been doing.
This election will be more about Trump than Biden which is probably a good thing for the Democrats. All we now need to do is to figure out how those pesky, finicky independents, swing voters view the two candidates.
It's high past time that we start electing Americans to congress and the presidency who put America first instead of their political party. For way too long we have been electing Republicans and Democrats who happen to be Americans instead of Americans who happen to be Republicans and Democrats.