I have a pretty old paperwhite. When it started deleting books i had side-loaded via calibre, I decided to get a kobo. I have a libra color, and I have to say: price notwithstanding, it's a great device. I don't have a lot of experience with more recent devices, but compared to my 2nd gen paperwhite, it is _amazing_. Color is good enough to read comic books on it, the google drive integration means it's not too hard…
But, with that all said... it's great for my specific uses. Android is just so much better if you want to run self-hosted stuff. When it dies or the software just gets that old I'll be really at a loss for what to get to replace it.