Unequivocally , version2! Iconic, to say the least. Remember how cool he looked on those Mike Zeck comic covers? As for the toy: The sculpting, the colors, the gear, the card-art, everything just came together to create the perfect storm of bad-assery. Perhaps the greatest action figure of all time... I love you
A very close second would be the last new sculpt version they did. Again, an excellent sculpt (which was not that common in the new-sculpt days), great colors, awesome accessories (how cool is that folding-stock mini-uzi). Admittedly, it had a few shortcomings, such as his poorly done hands that hinder his ability to hold his gear normally. While his ankle-holster didn't hold his knife too well, it is the perfect fit for any small handgun. This may be a minor nitpick, but the sword he came with was too bland and clunky. But Marauder John saved the day by giving us a 2-handed version of his original scimitar, which goes with this fig like peanut butter goes with chocolate! Sadly no card art to speak of, unless maybe you count the Bradstreet comic art that supposedly influenced this figure.
Version 3 was cooler in concept than in execution. Actually, the 25th version was an improvement and lives up to that concept! (And it pains me to say that!)
Hmmm... the ninja force figure was actually pretty cool. If it hadn't been totally ruined by the lack of o-ring and bad colors, it could have been a really cool figure. Cool little details, awesome headsculpt, too bad.
I also love a custom I made, which is basically version 4 in black, and another custom I got off e-bay a while ago.
And I have to admit, the 25th version 1 is a great looking figure.
My least favorite is listed as version 17 on YoJoe. Uninspired design, awful sculpting.
Oh yeah, I don't consider the T-crotch figures as Joes. And I don't count or buy repaints or frankenjoes, so there you go. Don't hate em, just not interested.
Wow, I can't believe I wrote so much about a little action figure! Must be love...

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O-ring is better. There. I said it.