Onyx Boox Go Color 6

I really like this device with the caveat that Onyx quality control is awful. If you get a good one (or play the return/exchange), you'll be pleased with a speedy device that can install other Android apps like Libby and Hoopla, in addition to ereader apps if you don't like the native one (it's good, but not perfect). Out of the box it wasn't ideal, but once I played with the settings, it works very well. Though if you want the small form factor and solely want to read, get a Kobo -- perfect fit for purpose and highly reliable (I had my Libra H2O for years and only replaced it because I wanted something to also take notes with. Indeed it still works perfectly as a pure ereader)

I also have a Daylight tablet from work I've played with and at first I thought it was merely fine, but it has really grown on me. If you don't mind the ~$700 price tag, it's super fast, the Live Paper display is fantastic, the writing feel is nice. Oh, and I like reading on it, too.