oneworld itinerary help
 

Will be using some BA miles to fly from EZE-Geneva-GIG open-jaw return in Business. My understanding is that I have to use at least two oneworld airlines other than BA. Does anyone have any suggestions as to which oneworld airline would offer the best product would this routing. I'm in more of a rush on the outbound and can take my time with connections on the return. I'm thinking of:
EZE-LHR(transit)-GVA on BA and then either GVA-MAD(transit)-SCL-GIG on IB/LanChile or GVA-MAD-MIA-GIG on IB/AA

Any suggestions would be much appreciated from this newbie oneworld flyer!

If I were you, I would not fly IB across the Atlantic. Everything seems fine on the outbound. But on the return I would recommend GVA-MAD on IB and then MAD-MIA-GIG on AA. I haven't look to see if the connections will work.