Kobo Sage (snappy, 8" display, a little on the heavy side) Screen is marvelous. Battery life, OK, but won't be as good as most e-readers. Dropbox and Google Drive support, stylus and notebook support.
Pocketbook Era (sometimes slower than my Oasis 2, sometimes faster, 7" display) Screen is nice, close to my Oasis 2, battery life good, has Pocketbook Cloud integration, so you can get sync for side-loaded books. Built-in speaker for audiobooks and text-to-speech.
Both are nice readers! Kobo Sage is more mainstream and with an easier UI, Pocketbook has some nice customization options for the UI. If you prefer a larger screen, go Kobo Sage, if you like a more compact 7" screen, the Pocketbook Era is a bit smaller than my Oasis 2.
I don't know how the Pocketbook store compares to the Kobo store. I plan on continuing to use the Kobo store for purchases.
You can see my thoughts on the Pocketbook Era at:
https://www.mobileread.com/forums/sh...d.php?t=362434
If I had to choose between the two, it would be Sage, hands down. But I am older, and I use slightly larger font-sizes (14-16pt) and love the amount of text I can have on the Sage screen. However, that said, you definitely get more text on the Pocketbook Era screen than you do with the Kindle Oasis, because the minimal margin setting is much smaller.
EDIT: If you are dependent on Kindle Whispersync and cloud backup of reading progress or annotations for Send-to-Kindle content, the Pocketbook Era might be your best bet. Kobo does not have sync available for side-loaded content, only for purchases from their store.