I've recently started using the Onyx Boox Nova. Before using the Onyx Boox Nova I've used the Likebook Mars and Boyue T80 (rebranded as Icarus Illumina XL). Overall, I prefer Android e-readers to mainstream e-readers. One of the positives of Android e-readers is the possibility to install third-party applications. Below is a list of applications that work well on E-Ink Android devices:
Simplenote: Simplenote is a note-taking application developed by Automattic (the company behind WordPress). It is a no frill scaled-down application to write text-only notes. It is possible to connect a Bluetooth keyboard to an Android e-reader to write quick notes in Simplenote and then access these notes on other devices.
Moon+ Reader Pro: Moon+ Reader is, in my view, the best Android e-reading application. The application isn't optimised for E-Ink but works relatively well with the right changes, e.g. side loading fonts with added weight, choosing the bold option for thinner fonts and turning the background white and text black. Another positive is that Moon+ Reader mainly uses a grey palette for its menus that are legible on E-Ink devices. Also, many Android e-reader vendors now support extra features to optimise third-party applications for E-Ink. One useful feature is the contrast enhancement of menus that make user interface menus clearer.
KOReader: This one is a no brainer. KOReader is designed and optimised specifically for E-Ink. It is a stand-alone application that can be used to read e-books and PDF documents. I found the application is more stable on Kobo devices due to hardware uniformity. Android e-readers, on the other hand, vary a lot and use different processors. For example, KOReader is stable on the Likebook Mars but the screen flickers on the Onyx Boox Nova when selecting menus and highlighting text (the only way to stop this flickering is to turn on A2 mode).
Librera Pro: Librera Pro is designed to work on both tablets and Android e-readers. For example, the application includes a PDF scroll mode that makes navigating pages smoother on an e-reader. Other options include contrast and brightness enhancement to make text appear bolder and darker. The monochrome menus are also designed to work on E-Ink.
Writer+: Writer+ is a stripped-down writer application. Writer+ supports text markdown – a useful feature as there is no need for animated user menus. One negative is that there is no option to manually change orientation to landscape. This is a problem as most Android e-readers don't support auto-rotation and, so far, Boyue and Onyx don't allow the user to manually rotate the display in third-party applications.
There are other applications that work on E-Ink Android devices. Other applications that are functional include Wikipedia, Kobo, Google Keep, Gmail and Amazon Kindle. However, many of these applications are designed with animated menus and colours that make text appear faded and navigation frustrating and slow. There are also very little options to manipulate text appearance in these applications. Both Boyue and Onyx support A2 mode to make downwards scrolling and internet browsing smoother, but the downside is a lot of ghosting. It is a definite positive that it is possible, for example, to read Wikipedia articles on an e-reader but it is more convenient to access these articles on a tablet, laptop or smartphone. The same applies to most Android applications.