I don't trust Amazon to not suddenly erase my reading material willy nilly, or shove utter crud into "My" Kindle, if I got one - reading PDFs is a pain using my Sony PRS-T2, screen's too small, but for ePubs it's fantastic.
I tried a 10.1" Lenovo M10 Android tablet for PDFs, but short battery life and heavy weight was a pain, besides I never know what the heck Lenovos might be doing surreptitiously to further the Chinese Government's famous secret World Domination Plan (I've applied electrical tape squares over the cameras - there is no hardware switch for the microphone(s?) and I should rip it/them out), so I've recently been trying to read PDFs using my newly upgraded old 8" Sony VAIO P, which now has a fast and much larger mSATA installed in lieu of it's original slooow and tiny hard drive and... it's a pain because of it's madly proprtioned screen:1600 pixels wide and 768 pixels high, for which there appears to be no other resolution available which fills the screen and doesn't alter the geometry of very localised space-time, making the lettering look like it's being stretched to the side by a passing micro-black hole... and the interface of PDF reading applications are so damned tiny when aspect ratio is correct, at 1600 X 768, I have to use a screen magnifier (Windows>Accessories etc, Magnus in Linux), in order to see anything of the miniscule controls to enable further reading... plus controlling the mouse is a pain, unless I use my Logitech M570 wireless trackball... but happily battery life is now over five hours (thanks to the mSATA, was a little under four hours when reading, before upgrade)... so I was looking at the ReMarkable last week, but the moment I saw the stupid pricing for the styluses, at silly extra, I made a nasty ReMark and smelled a rat; it wasn't in my kitchen.
I continue looking out for a cheapo deal on an OONX BOOX, which supports the widest variety of file formats, and has a significantly larger screen than my Sony PRS-T2. It's a pity Sony exited the eReader market, because despite being too small for PDFs, in many other respects the Sony PRS-T2 is an excellent reading and note taking device, and not their only success in that space. Sadly, I don't have the version with the hackable firmware, which allows installation of a full version of Android - if their screens weren't too darned small, I'd find one.