Using a Windows tablet as an e-reader is not something I would recommend but there are some applications that can make it work. Below is a list of recommended applications:
E-Books - The choices are limited for e-book reading applications, in comparison to Android; Book Bazaar is the best standalone option, with Frida being a second option. Amazon's Kindle is poorly supported and the only viable option, after Amazon discontinued their Windows Store application, is to download the cumbersome and poor PC version of the application. Oddly, Amazon support an Audible application in the Windows Store. Both OverDrive and Kobo support good applications that are downloadable from the Windows Store.
PDF documents - Adobe Reader Touch, XODO PDF Reader & Editor and Foxit Mobile PDF are all good options that allow the user to annotate and edit PDF documents.
Note taking - OneNote is the better option as it is fully integrated into the Windows eco-system and there is no subscriptions cost restrictions similar to Evernote.
Cloud storage - similar to OneNote the choice would be to use Window's native OneDrive for cloud storage to sync reading between devices. However, there is a Dropbox application in the Windows Store.
Finally, there are a lot of refurbished Windows tablets but three issues should come first when choosing the right one - (1) battery life; (2) minimum 2GB RAM; (3) minimum 1280 X 800 resolution.