For me this is an easy one. Leveron.
Vancouver I think made a great move in getting this CB. He is only 23, and while we do not know how much they had to pay for him, if it is not a huge amount then I think they get a solid player who can make the starting XI right now, who already has a lot of interest from euro clubs and who the team can sell in a year or two and possibly make a lot of money on.
This position might be our weakest even with the signing of Silvestre (although I really like DTG and AJB and I think Mosco can still be a solid starter or in the 18 guy). Leveron would probably start for the Timbers and would make dropping Horst and/or Futty an easy decision (my view would be Horst as I think he has more trade value and heck I love Futty).
Your one who got away?