I tend to use OB-6 with the filter rolled back a lot, because it does excel at mellow impressionistic sounds, organs and with more woodwind-like resonance. Actually some of my favorite patches are with one osc and the second as a modulator. A little noise added, not much sub if any. Simple is better.
The FM and filter modulation can sound quite good, too, but again with the filter rolled back.
The old Oberheim filters sound more liquid and the resonance saturates a bit more at the peak. That is also true of the Prophet 6 vs 5 or 600.
The Super 6 FPGA oscillators sounds a bit too static for me for analog sounds. Not much drift, but maybe that can be emulated better. Presumably the analog filters are also more stable across voices than the old synths. I like the demos more when it does hybrid pad sounds. It does have a lot of character overall, though. Definitely more dusty than the Novations. Probably as good as we’re going to get these days.
One of the nice things about the OB-6 (more so than the Prophet 6, and this is by design) is it doesn’t sound entirely stable.
If you want a synth with a good filter, I think an old one is still nice to have. Most of the modern options have pretty brittle filters. I tend to prefer the Waldorf digital filters to them. But again, the Waldorfs don’t excel at analog-like sounds but at evolving pads.
One of my favorite synths is the Prophet 600 with GliGli teensy mod, because it adds a lot of LFO options (especially like noise shape, and delayed onset), faster envelopes, and velocity control with external keyboard.
All that said, there’s always demos that bring out the best qualities of a synth. There are a lot of good rev 2 demos, even though it’s not my favorite sounding synth in terms of raw character.