It should also be mentioned that Sannies Jack is descended from the original Sensi release...
To be clear, Sannie took the original Jack Herer from Sensi, and has inbred it for 7 generations selecting for what he thinks are the best characteristics of that line.
So while his is descended from "Jack Herer" it isn't exactly the same thing as the original. Whether or not its "better" or "worse" is somewhat subjective, but I haven't yet heard anyone say anything bad about his version. If I were buying, his is the one I'd buy.
Also supposedly Sensi Se-eds lost the original parents of its version several years ago, and what they are selling now is basically a re-creation that some feel isn't as good as the original. I don't know this to be true, but so I've heard.
In any case, it well may be fair to say that NOBODY is offereing the "true" Jack Herer as ceeds anymore. Unless you're growing a plant cloned from a years-old original Sensi plant, or growing ceeds from a years-old pack of Sensi, you're probably growing either a copy of the original or a line descendant.
Note also that there are several other lines out there that are other peoples renditions of the same (ie the tongue in cheek named "Jock Horror"), or plants bred from a similar lineage (eg Super Silver Haze) that are also worth considering if this is something you'd want to grow.