Many heroes and villains are routinely accompanied by others allied to their cause. Alliances are not uncommon, what does seem uncommon is actual friendship among them. For example Superman and Batman. They work together all the time and confide in each other, but an actual friendship? It's hard to picture either one calling up the other to hang out during their down time, taking vacations together, or Superman calling Batman cause he needs someone to talk to when Lois's Aunt Flo is visiting. Guy Gardener and Kyle Rayner on the other hand are close as brothers. So the question is which hero or villain has the most actual friends among the hero or villain community?
He's friends with a lot of old guard due to his time as Robin, he's the leader of various Titans who are very very tight with him, and he's also a big brother/mentor to Tim Drake and Damian.
Nightwing probably has the most connections in DC and was often stated to being one of the best leaders in the superhero community. Pretty much everyone liked and respected Grayson.