So far I think from best to wrost, (but I'm not so sure) it's

1. Plan B VCO Sine (good)
2. Tip Top Audio VCO (a little better than Analogue Systems Never
owned one of these)
3. Analogue Systems VCO Sine (bad)
4. Doepfer A-110 (worse)

Laryn91, your vintage MODULES or your vintage tabletop/rack/keyboard
synths Don't forget that all my filter modules produce very clean
sines. Also, I believe the quality of the sine has to do with its
oscillator core. I think to get a clean sine requires a second VCO
within a VCO... as in, one module has to house two different
oscillator cores. One for square,tri,saw, and another separate one for
sine... but I don't know anything about circuit boards, this is just
my guess. I think this is easily done in a self-contained synth like
your vintage gear because it's one whole system, not a bunch of
modules... or something... know what I mean