There is a comment in 1 Timothy 3:2 about how a bishop needs to have only been married once, clearly indicating that monogamy is better. Jesus’ comments in Matthew 19 also are spoken of in the singular, indicating monogamy as God’s intention.
Anything more would require piecing together all the Bible says about marriage. At that point, it becomes clearer why we reject polygamy, but it may not please those who refuse to accept anything not explicitly stated. (I know some would call that sola scriptura, but that’s at most a very extreme take on the doctrine.)
He also talks about how “so many in Genesis and the Old Testament were polygamous or polyamorous.”
That’s a very similar, albeit weaker, objection to the one the Pharisees made in Matthew 19 when Jesus opposed divorce. Jesus was, of course, unmoved by such an objection.
they would have to choose a favorite and divorce the others which is also sinful…
I’m not sure why he believes that.
If the marriages followed sequentially, so that there was a clear “first marriage”, it would see very clear that only that first marriage is valid. All others were made in sin of adultery.
If it isn’t so clear, then it still isn’t sinful to “pick a favorite”. The person wouldn’t even need to “pick a favorite”, as all the “marriages” could be reasonably seen as invalid. If they do, though, the pain isn’t sinful but a consequence of past sin. That’s one potential problem when sin is committed - you get hurt when you and/or someone you’re doing it with chooses to stop committing it.