I'm all ears.
I don't read much about mainstream thought so there might actually be one but no one has ever mentioned it. You can find pages on the web jam packed with all sorts of ramp designs favored by variuous egyptologists but I've not seen any other proposals except for the occasional suggestion that cranes or levering were used for some stones. I've seen lots of different ideas from before middle of the 19th century before ramps became accepted.
Look at pg 216 in "The Complete Pyramids". Better yet read the caption. The chapter is headed "The question of what kind of ramp was used...,".
Sorry, but ramps are the only really accepted means and are the one most easily shown were not used.