OV-10/AH1
JG
The Marine Corps needs differ and at the time the OV-10 flew for them and differ now greatly. The Cobra offered CAS at a very basic level of the MAGTF, the MEU where little or no host country considerations occur The other required a host country at the same basic level (even though it wasn't organic to a MEU), or if operating at a MEB or MEF force level, required you to trample down the doors to set up some sort of forward operating base.
These being closer in mission and deployability than other helo/fw combos you have listed, yet worlds apart and not to be considered in the same bucket.