I bought a Remarkable. A completely different type of e-reader. While overly expensive I would say it represents the future evolution of e-readers. Mostly focused around realistic writing feel, making it easier to read .pdf and less eye strain.
Indeed, personally I just purchased the Onyx Boox Max 2, a 13 inches e-ink tablet running Android (6.0). quite expensive (some will say far too expensive if compared to iPad pro, but keep in mind its niche market, small company, R&D).
PDF is quite well support, and now we start seeing Android apps with special mode for e-ink (Librera).