Depend of the angle (worst in the sense, both team were hurt, or worst in the sense the greatest for one of the 2 team)
Yashin was sent to the New York Islanders for defenseman Zdeno Chára, forward Bill Muckalt and the second overall draft selection, which the Senators used to draft highly touted centerman Jason Spezza. Islanders' GM Mike Milbury promptly re-signed Yashin to an enormous 10-year, $87.5 million USD contract.
Senator got: Chára (Norris level defenceman in is prime) Spezza (one of the most thought prospect that have a really good run with them)
For Yashin, that didn't even stay in the league, that the Islander had to pay with him not even in the league for a long time (at least he was still on their cap for a long time).
The Habs was involved in a couple.
The Seals' 1971 trading their first round pick (Guy Lafleur) was pretty terrible for them.