Paperwrite gen 12 signature edition or another e-reader

Hello guys and girls,

I've been using FBReader for years, but as I'm getting older, my eyes aren't as good as they used to be. I ordered a Paperwhite Signature Edition for 150 EUR on Prime Day, but since I've never used an e-reader except an old Kindle 3, I didn't even know there were other good options. What would you advise me — is it better to return it and buy something better, since I won't buy books directly from Amazon? Or is it good enough for me — I can always use Calibre.