In the modern era(1968 up) my pick would be Gilbert Perreault. I paid quite a bit of money for a PSA 7 that looked too nice and it turned into an SGC 88.
Opinions welcome.

If it looked nicer than 7, I'd first re-send it to PSA.

1968 OPC Bernie Parent (RC)

From personal experience of trying to finish the set, I would vote for 1972 OPC #213 Don Lever.

That particular card was discussed here last year, and even with the knowledge that a specific collector wins them at all cost, no matter what condition, I placed a ridiculous bid on a PSA 8 and still didn't win. It sold for over $400. So the card itself is tough, but there is no chance of getting one at a reasonable (or even unreasonable) price either.

I think there are only 7 PSA 8's an 1 PSA 9.

I also agree the Perreault is very tough.