Kobo store is convenient but feels pricey sometimes (I don't have experience with the Kindle store). I don't mind paying them though, because it's still easy enough to strip the DRM and make backup copies of my books. If that changes, I'll take my business elsewhere.
I make a lot of use of my local library through the native Overdrive integration.
I make a lot of use of my local library through the native Overdrive integration.