Amsterdam to Copenhagen

It's a 9 hour drive or 11-hour train ride so I'm thinking a 1-hour flight on KLM would meet my definition of "best."

Yes, fly - unless there’s a specific reason for you to take the slow route and spend all day on the road/rails.

In addition to KLM: SAS, Norwegian and Easyjet also fly direct AMS-CPH.

Thank you! My thoughts as well, but just wanted some other opinions.