Personally, I want emotes like "Luck was on your side this time", or "I'm Bored, can you go faster? Please?" or maybe for thoose decks that you face all the time "Pah...how original..."
I'm really bummed that I am forced to be nice to the opponent all the time. Ofcourse, thoose salty emotes should be on a longer cooldown to prevent spamming.