I had a long thread about this a few months back. Here it is, for those who may be interested.
https://uselectionatlas.org/FORUM/index.php?topic=6426.0For those who don't want to read pages upon pages, I'll sum it up.
The Republican party is controlled by the wealthy and to a somewhat lesser extent the "religious right". Everything that the party leaders do is to the betterment of this unholy alliance, not what's best for America.
The Democrats, for all their flaws, are the only party that stands up for tolerance, social justice, and economic opportunity for all.