I've bought multiple '90s S100s for ~$700 or so, and it's 10X the instrument you'll get from a Newark Street Guild. I got my NS Guild for $500 used, and for the additional $200 I'd always pick the '90s model. For the $600-800 I usually see the NS models priced at, it's a no-brainer to me to get a Westerly example, though you might have to be patient to find one for ~$700. I also totally get that being patient sucks. :emmersed:
As for your actual question, I don't know of any years being better than others. There is an absolute glut of them in the market, though, which is why if you're patient (ugh) you can get one for ~500.