Gotta be the Lindros deal by far!
Here:
ON JUNE 30, 1992, Lindros was sent to the Flyers for Peter Forsberg, Mike Ricci, Ron Hextall, Chris Simon, Kerry Huffman, Steve Duchesne, two first-round picks (one used to select Jocelyn Thibault and the other traded twice, eventually used by the Capitals to draft Nolan Baumgartner) and $15 million.
Each of those guys were used to get people like Roy, Bourque, Blake to the Avs. Gotta be the most lopsided trade in retrospect.