Oh man, way to ruin my tough guy image! Guys I enjoy negotiations with the most are Dinger, NJH, FTD, Cats Ass, BTS, P2F and Fatcox.
Basically number one thing for me is dialogue and reasoning. If I send an inquiry, do you respond, how quickly and you tell me what you want. I hate negotiating with people who have it in their mind that they are going to get the better end of the deal and won't budge on their asking price no matter how much you reason with them. If you don't want to move a guy for what I'm offering, explain why and what you'd want to get it done instead.
I do like Silvio, though I hate drafting with him, he's just too aggressive in pushing his players and they are almost exclusively guys he just wants to get rid of. GD is really bad for not compromising which is frustrating in the BBDL but it obviously works for him, just I won't be having any part of that. Those are the two guys that stick out.