My trusty K3 (along with that leather cover with a lamp

) got stolen recently, and I haven't been able to decide which e-reader should I get instead.
I'm not against getting another K3 (I did like the keyboard a lot), but since the contrast and ppi of e-paper has gotten better since I bought it right after its release, I'd rather buy a reader with a prettier display.
A hard requirement for me is e-ink and physical page switch buttons, and some sort of Instapaper (or Readability or other article service) support - I used its service that sends a digest of articles to your @kindle.com address which worked okay, but I'm sure there's other options besides that.
From what I understood, for instance, there are some e-readers that run full on Android? Would I be just able to install the Instapaper app then? But don't the Android readers have worse battery life than e-readers which run a stripped down optimized OS?
Other than that, I have no strict requirements - I didn't use the Amazon shop so I don't need it; I'd like to read a bit of manga too, but I'm fine with converting it to whatever format necessary (same goes for epub/mobi).
Thanks in advance!