I've had both a Clara and a Libra, and would recommend the Libra. The bigger screen is great, and I love the buttons. Getting around the Kobo registration is NOT that "tedious" at all, it simply requires a fake email address.
zxjoanw@nosuchword.com would work fine
I have no experience with the Pocketbook, but if you do choose a Kobo, you would not regret either one. Clara HD is a great little reader, the Libra a great not-so-little reader.