In order, my preferences are:

1) Mapudungun
2) Guaraní
3) Aymara
4) Quechua

not that I wouldn't want to do Quechua, I'd just like to do the others more.

But you are certainly right that African languages are cool. Kinyarwanda or Fula would be my votes, but Akan is cool too. But again, resources.