If we're going based on beliefs alone, the Raëlists or Nation of Islam take it hands down. The Dr. Yakub stuff is hilarious and serves as a source of inspiration and courage in my personal life.
However in practices it's gotta be the Scientologists. Bizarre how they've been able to continue doing it for so long.
A big headed scientist using eugenics on a Greek Island thousands of years ago makes no sense. It also is nothing like what most Muslims believe.
The Nation of Islam is so unlike mainstream Islam that the name itself is almost impossible to understand, yeah. They don't even believe in an afterlife.
They're not even monotheistic.