Steve Largent, hands down.
Why? Because somebody in the Seahawks Organization saw something special (imho) and got Seattle transcendent player that seemed as "Plain Jane" as it gets. But that player put the Seahawks on the map and announced their arrival in the NFL in a BIG way!
It's not too uncommon to see a trade made that nets a team a player that everyone expects to be good, but to get a "nobody" for an 8th round pick and to have that man set the record for receiving touchdowns while playing on an upstart team with who at Quarterback? Some kid with tiny hands from the non-existent Milton College? I
One could see 100 touchdowns by a receiver on a perennial playoff team, where they play extra games every year. And such a receiver that played from the 80s onward when rules were changed to benefit offenses, would have an easier time reaching 100 TDs than Steve Largent did.
So IMHO, this is the best trade ever for what we have up, what little was expected out of what we got, and the fact that the player we got, ended up in the Hall of Fame!
All those other players? They are expected to be good, so everyone saw the value of the trade. I'm sure many said "Who? What? Meh."