I have bought 2 Jiayu G4 Basic phones so far and been very happy with them both. As far as I am aware the G4 Advanced isnt available to international customer yet??
It depends what you want. Only the “Basic” (dont know what its called) version of the Neo has shipped as far as I am aware so the 1GB RAM and 4GB ROM and 3000mAH is same specs as the G4 Basic.
The only differences then are the G4 is slightly smaller (4.7inch screen instead of 5inch) and lower resolution (780P for Jiayu and 1080 for Neo) which means that with the same processor, RAM and battery the Jiayu should run faster and battery should last longer but under close inspection the Neo might look clearer (I haven’t noticed any pixelation with the G4 but Ive never owned a 1080P phone so others might be able to give better feedback).
The other difference is that the Neo is supposed to have MHL (haven’t heard any confirmation in current shipment) so if that that is an advantage to you then might be worth considering.
Personally I can get the Jiayu G4 Basic running slowly with some games so I am waiting for the Advanced Black to be available. I would choose the G4 over the Neo because I don’t need MHL or a 5inchscreen. Slightly smaller screen, slightly better performance and battery life is more important to me. Also I have heard issues about build quality of previous Neo phones so until there is reviews on them I would hold off. The G4 feels to be a solid phone and build quality is good. With the touch screen update and the GPS fix (both in the “How To” section of this site) I haven’t had any issues or complaints. Occasionally in Navigation it will have me tracking 20 metres north of my actual location or something but running GPS Test app fixes that instantly.
Hope that helps, if I am wrong with anything I’m sure someone will correct me