[tomsem]

I have no experience with Kobo Libra 2, but have the other two.

Paperwhite display is maybe a little better (Era is very good though) but customization is nil, and it is not as friendly to side loaded books, to say the least. Send To Kindle service is usually more convenient and works well, but metadata other than author/title means nothing.

PocketBook platform is great, very friendly to third party content (I don't even know how to buy anything from their store in the US): syncs to PocketBook Cloud, works with DropBox. It does have AZW/AZW3 support, but I just feed it ePub. You can browse content by tags, series, author, format, collection, folder -- very flexible.

I can download from calibre server or cloud storage (OneDrive) using web browser. If I open with the app, it syncs and I can download to the Era after a few minutes. The apps should work with calibre server, as you can connect to OPDS services, but after connecting all I see is label 'calibre' and there is no browsing to be had (I have been meaning to debug it). But of course you can just use a web browser to connect to calibre, and then share the download with the app.

I am also a fan of text to speech (available in multiple languages), and it has built in speaker and plays audiobooks (Mp3/m4b) in background so if you have the text, you can follow along. Also a music player (also plays in background). And of course Bluetooth audio support.

On the downside, there are no justification options (I like left-justify), and there is no way to adjust font weight (apart from setting everything to Bold!).

The Android and iOS apps also have text to speech (and justification options), and have auto-scroll, which I use on my iPhone.

Both the buttons and (the 9) tap zones can be configured. You can annotate with fingertip or stylus, there's a little suite of apps and games.

Also you can install KOReader very easily, if you prefer having control over everything.

It should be possible to borrow from public library using the web browser, but I've not tried it. It generates an AdobeID that syncs between devices and apps linked to your PocketBook account (again, I've never tried it).

While the form factor is similar to Libra 2, the latter reminds me too much of the Oasis I once had, and I found the button placement uncomfortable for my hands. Era has them out of the way so I'm not pressing them accidentally, and I don't have to keep my thumb anchored to a particular location.

It does not have text to speech or a speaker, and Kobo does not provide storage for 3rd party content (I guess you can use other cloud services for this). I don't like the Kobo iOS or Android apps, compared to PocketBook or Kindle.