I have bought both a Kindle and Kobo at two previous times. Both bought via Amazon.
Kindle vs Kobo is like Apple vs Android.
For me, Kobo is the better one as who admires freedom and flexibility. I can read epub format there, but Kindle does not allow it. Also, Kindle has so much restrictions (similar to Apple ecosystem) when connecting with external devices and copying books. Amazon Kindle has better build quality and long lasting battery life than Kobo.
If you have lot of books in epub format, buy a Kobo. But if you are willing to buy e-books from Amazon, then it's better be a Kindle.