JFK, surely.
To be fair to Joe now he didn't actually sign anybody. Anybody who payed 8 Mil for Boumsong, 18 Mil for Owen and 9 Mil for Luque is pretty s****. Can't remember us ever paying so much, for so many with so little talent.
Hindsight is 20/20, but those two were great coups at the time, imho.
According to Souness those signings were made by Shepard he wanted Anelka and Boa morte