Idk...I generally care more about the group and topic than the platform. As for the platform, i think i like irc the most, but haven't been on in some time. Kinda lost interest in what most folks have to say.
Tried fb for a while, but as a platform, it sucks. Too much incentive for trolling and shitposting.
Ychat was nice back when they had groups. Not sure if they still do that or not.