I use gg because it's all one key. With gf you have to use separate keys and I'm used to saying gg anyway. But, I will say gf back to someone if they say gf first.
Saying good game or good fight is a sign of respect towards your fellow toribasher. So I think it should be said no matter if the match was really legitimate or not.... Just my humble opinion.
I agree, I almost always say gg as a sign of respect and politeness.
[22:26] million: someday, we're gonna destroy space-time
[22:26] million: I'd like to be partly responsible