Trying to get away from my phone more, and an e reader sounds like a good way to get myself to read more. Kobo is sounding like the most recommended one based on some googling, but I’m also ok with jailbreaking something like an older kindle from eBay. Something that plays nice with Libby would be ideal but not required. 
yeah kobo will do you well. i had koreader on a kindle but it kept resetting itself and fucking me over. i do recommend setting the option to wake the battery with a magnetized cover off on the kobo, for some reason it drained my battery, probably from bumping around in my backpack