If you lost, and it was not a good game from your point of view, why not simply say: Congratulations?
Because no matter what you say, someone is going to find a way to get offended by it. There's no way around it; those people are professionals and you can't beat them.
lol
In USCF it's usual practiced to shake hands and say good game. I personally dont care either way if we say GG here on chess.com, but I do get a chuckle every once in a while when I tell somebody that has just beaten me, good game, and they reply Thank You.
They dont know the reponse should simply be good game or gg. I'm not giving you a compliment by saying good game, it's just chess etiquette that I'm used to from OTB. It's like asking somebody how they are doing (small talk) and they respond with some crazy long drawn out story of there life. I dont really care how your doing, but your just supposed to say I'm fine, how are you?
LOL. OK now I'm just ranting, Yeah I dont care either way on chess.com if people chat. I'm just here to play chess, but will gladly strike up a conversation.