750Ti every time, preferably in "SC" variant. Keep in mind though that even if you mine most profitable coin with it, current ROI per card is around 500 days.
that the number you get, if you don't try to think about what you mine... (using your brain helps a bit at that level...)edit: if you need 1 year and half to make 120euros... may-be it is better to stop mining...
you will probably make more with a metal detector on the beach... (or just saving one euro everyday... actually this solution will pay you 3 gtx750ti over your 500days)