Iv tried spinosa in kruger game reserve in S.A and it was nice but lots of seeds. The one I tried was just wild in the bushveld and not cultivated though and seeds are said to be very variable.
I haven't tried S.pungens or any other strychnos sp. so I can't comment on what is best.
I'm happy to give people the one I think is Spinosa just for cost of postage. The S.pungens I'm buying for myself from a vendor so I can just order more if anyone wants I just ask you pay postage and cost price it's like 4/5$ for a pkt which I think is around ten. I'm also getting Marula seeds at the same time if anyone wants.