Well, to me, the king is still an Eminent 310 Unique, paired with at Smallstone phaser from the 70s... That is what Jarre used... The eminent even had a built in spring reverb and analogue ensemble chorus.... And the ensemble chorus is exactly what creates this peculiar stringer sound... The raw tone going into this ensemble fx is basically just a sawtooth, but in general you could throw other simple waveforms into it and get that tone just with a different flavor... Thus the real stringer magic for me is not the tone generators, but rather the effects they use... Ensemble, phaser and spring reverb... Find an effect processor that could get those three right, and you could make a stringer synth out of any synth.