I am not sure if bibliotik has more books than libgen by sheer numbers but I am pretty sure that bibliotiks books are of higher quality and better organized at the very least. Oh and if you haven't already got your foot in the door or know somebody who does it is unlikely that people like you and I will simply get invited by some kind stranger on the internet.
Also, a lot of books that were behind the bibliotik signup wall have been freed by /u/-Archivist.
I personally recommend you start with MyAnonamouse.org. They hold invite interviews twice a week over IRC and I have heard that the community is really welcoming to new users.
