G.I. Joe wins. Shield might have better overall tech, but most of the Joe's named characters (who are rather numerous) are mid-high streets and their best characters (stormshadow, Jinx, Snake eyes) are low metas.
if I get the chance, I will post scans (it'll be a little tough because some of their better feats happened a while ago). What really matters is that cap is the highest level characyer that shield has (so any metas that are higher than him (quake) are out). Meanwhile, G.I. Joe has a vast amount of average mooks (nameless soldiers) and a far larger (relative to shield) amount of named characters. They have people that operate in low light situations, experts in infiltration who don't hesitate to kill their own if it furthers the cause, and unlike shield, they haven't gotten every base that belongs to them blown up at one time or another. Admittedly, this whole battle depends on where they're fighting and if they're allowed to retreat or prep. Also, I'm using the IDW version of them (who are currently dealing with shape shifting aliens) and who've stopped/ended multiple insurgencies and wars.
I will admit, the cartoon version of them gets curbstomped.
I don't think I have read an actual JOE comic but conventional warfare is pretty much what they do 24/7 and Shield is pretty much fodder for the bad guy till the heroes show up. I am sure this isnt totally correct so take it with a grain of salt please.
you're not actually incorrect. How often have we seen a single character go around beating on all of shield? Meanwhile, the Joes deal with legit terrorists, gangs, drug lords and warlords. Off the top of my head, I recall Chuckles (who is not on the level of Scarlet, Duke, Roadblock, etc) casually disarming and killing a small group of military members, killing another group of assasins, surviving multiple warzones, and even surviving a suicide bomber blowing up right nest to him.
Thats what I was getting at but the hard part for me is SHIELDs opponents are usually giant Godzilla like Monsters or superfreaks that would also mop the floor with the JOEs so its kind of a coin toss for me.
I won't outright argue for Shield winning cause I don't know a lot about the comic version of GI Joe and Shield's membership is always up in the air, but I will say that Shield has had a lot more named characters than folks seem to be giving them credit for. Even if we cap their membership at Steve, it's still got potential access to guys like Nick Fury, Blackwidow, Hawkeye, Mocking Bird, Diamond Back, Sam Wilson, Mulitple Man, and any number of other accomplished members.
they've also gotten stomped on by street levelers though. Again, in a fight on a flat area, shield wins. But if this war can take place on multiple battlefields, the Joes can pull though.