I have a #Kindle Paperwhite 2 bought 8-9 years ago. Works perfectly with #Calibre, including Amazon's Whispersync. Use it almost daily, still in tip top shape. Most of my library is in .mobi format. Great piece of hardware, has served me well.

I've got a refurbed Kobo, which works well with #Calibre (a #FOSS #eBook manager) and supports epubs