Isn't saying nothing worse than saying GG?
Not if you won. Give the loser a chance to start any post game communication. OTB I will always give the loser the chance to initiate the handshake. In CC chess, the proper thing for the winner to say is "Thanks for the game". It has a better chance of being appreciated, if you send it the next day after the resignation.
Sending it the next day seems alittle long to wait, doesn't it?
... "Thanks" is a good phrase to say in the post game. :)