Riker and Troi were of course married so I suppose she would be most deserving of this title. However Riker and Worf often engaged to bat'leth training games on the holodeck, so he too is another candidate. Further it would seem the he was in good standing with all of the other senior officers on the ship, he could have been considered close with all of them thus the matter is one's own opinion.
It might have also have been Paul Rice, seen in the ST:TNG episode "Arsenal of Freedom". ProfessorTrek 02:19, July 1, 2011 (UTC)