Best Kindle PaperWhite alternative?

Current Paperwhite 11th gen user. I generally prefer to side-load books or use Libby's epub feature. Are there a series of Libby supported devices that are like a Paperwhite? For other instances, most of the time it's cheaper to buy a physical copy of the book than the Kindle version so I just do that.

For folks that have migrated due to the incremental changes from Amazon, are there e-Readers you have migrated to or are considering that you are very happy with?