There are atleast 4? good growers that sell Cephs on E-bay with a small amount of time you can figure out who is who. Otherwise buyer beware.
If I had to pick only 1 clone it would be the Squat, followed by the Emu Point clone I have (not all Cephs named Emu Point are the same, its a location not a clone so who knows how many clones of Emu Point are in the US), followed by Big Boy, then Czech Giant. Little warning...the Squat clone has a reputation of being a more delicate Ceph, so beware. May be true, may not.
I have received two HG from different sources, both I believe are traceable back to the original grower and have never had anything "special" from that clone that I have not gotten with the Emu clone or the Big Boy clone. If it makes you feel better about your choice...if I removed all the labels from all my Cephs I could only ID one type of clone...the Squat, everything else is VERY subjective.
As for the German Giant it has been the slowest, hardest to propagate, and lest note worthy Ceph I have. Any typical I have ever grown was better in every way. Maybe it just doesn't like my conditions.
If you haven't already check out
http://www.terraforums.com/forums/showthread.php/134965-Cephalotus-consolidated/page4 everything I know about Ceph clones/names is there.
Just be careful of named Cephs, I know I could rename this one and sell it as a new clone due to the color, which has nothing to do with the clone its the LED lighting it was growing under.
DSC_0167 by
randallsimpson, on Flickr