Intriguing.. Historically both organizations have had a significant role in african-american history, especially in social and political activism. Today, neither are what they used to be.. there exist splinter sects of both, all declaring that they are the true keepers of the original values.. Both had charasmatic leaders in their 'heyday', mainstream-culture hostility, COINTELPRO infiltration, and faced both scorn and respect in certain social circles of black communities.. free breakfast programs.. tutoring programs.. self-defense classes.. uplifting afrocentric thought..
If "forced" to choose, I'd say the Panthers, if only because the Panthers (generally?) had no quarrel with collaborating with like-minded white folks, and I'm not sure that I'd be allowed that flexibility in the Nation; that and my own ambivalence at flirting with hardline religious tenets and the lack of social freedom implied..