Well, if we're all going to share our accessory choice...
My blueshirt troopers are armed with the original AK-47s John made. Due to the wood stock AKs having only recently been restocked, I had to split between wood stock and folding stock AKs. My officers use MAC-10s and Dragunovs or RPGs.
AK-47 (wooden stock)
AK-47 (folding stock)
MAC-10
Dragunov sniper rifle
RPG
My standard Vipers are all armed with AK-74s with grenade launcher. It's just the ideal terrorist infantry weapon. I know they made an "NVR" replacement rifle, but it looks WAAAAAY too high-end for it to be the standard issue Cobra infantry rifle. An AK-74 is the way to go.
AK-74 w/grenade launcher
My Crimson Guards are all armed with AK-74s with bayonets, as well as a pump shotgun as backup piece.
AK-74 w/bayonet
Pump shotgun
My Night Ops Crimson Guards (CG 6-pack Fireflies with Chap Mei heads) are all armed with silenced P-90s.
P-90
My Alley-Vipers are all equipped with AKS-74Us, their compact size and effectiveness make them perfect for urban combat.
AKS-74U
Both M4s released by Marauder have found their way to various Joes. Too many for me to list, but just to give examples Hit'N'Run uses the classic one and Recoil uses the one with shotgun.
M-4
M-4 w/shotgun
That's it for army built characters or in the Joes' case weapons I've found multiple uses for. If I get into what I've given to each individuals, that'll take WAAAAAAY too long to list.
The bottom line is, Marauder Inc's stuff kicks the ass of any weapon made by Hasbro or BBI.