In my case it's mostly a view of who I think is the least appropriate candidate, which would be Trump. It's not that I think Harris is good but rather that Trump is exceptionally lacking of important qualities. He runs things too much based on ego and his own whims. It's not just that he's rambling arbitrarily when he's speaking, that kind of erratic thinking really seems to make its way into his decision making. It was never more clear than when the Covid crisis happened and he was flailing all over the place with his attitude towards it (including his trademark facts that he seemingly makes up on the spot), leaving the US worse prepared than if he had taken it seriously by listening to people that know better. There I think Harris will at least be better suited to listen to people that understand matters better than she does. I don't have any problems believing that Trump is susceptible to flattering manipulation either.
I also don't think he's very good for the west when it comes to foreign policy, and I do believe that it's quite important for the west to stick together as China keeps growing in power (and that's likely to continue despite current hardships, as they play a long game), etc. I think he did some good, like telling NATO countries to hold up to the terms they've signed onto, but he did still do plenty of poor things, like strain the relationship between USA and Europe. That fact was most likely something Russia banked on when they tried to extort Europe through gas deliveries before the war. They hoped that the west was now divided to the point where getting it worse economically would be a bigger deal than solidarity. Fortunately they were wrong but their gamble still wasn't too wild. Trump also not understanding how much better it works to pressure China if he can get Europe to join him just shows that he's not good at dealing with situations where he's not at the top and holding most of the cards himself.
So it's not that I want Harris because she stands out in a positive way in general. I think she can be depended on to be a stable and predictable politician, which is enough to be way more suited than Trump.