Champion N9Y............I thought these fitted all cars.............they did
when I was a lad.

Depends on the car. Some run great with fancy plugs, some run worse.

If the manual recommends NGK that's what I'd use absent overwhelming
empirical evidence to the contrary.

I used to second guess the engineers and try to do different things with my
plugs. I've decided that the engineers know better than I, and now I select
exact replacements for my plugs. I might go for Platinum, but I always
select the single-electrode plugs if that is what my car came with.

I once bought a set ot plugs from the catalog, then went home and installed
them. The car ran like sh.t, and took me hours to trouble shoot. I could
barely drive it to the shop where they put it on the scope. It turns out
that my factory plugs were something like 123C-xxs, and the replacement
plugs were 123-xxs. The "C" was a very important character -- it meant that
the plug was the "high output" type instead of the standard type. Now, I
pull a plug, and drive a different car to go buy more just like it.