vintage versus modern speakers

This is an easy one. No. Technology has advanced and the products evolved. You are better off with newer speakers at all price points.

Of course speakers from the 70s that are still around are old and not even as good as they were back then.

I don't think it's even debatable but hey you never know....

I agree with Mapman to a point.

The JBL L100 Century was and is still one of the best rock-
n-roll speakers ever made, if they're in good shape.

The Infinity Gamma, Beta, Sigma, some of the RS series are
still very good, again, if in good shape. One of the only
speakers I've ever regretted selling out of the hundreds of
speakers I've owned were my Betas. I still kick myself in
the ass every so often to remind me of what a dip shit I was
for selling them.

So it really depends on the speaker model and the condition,
but for the most part, today's speakers are better.