If you reply, or retweet with quotes someone who is hating your faves, you are helping that tweet (or post) to be viewed more.
It doesn't matter if you give the best rebuttal or the meanest counter attack, you give them what they want.
Block is the way to go.
I even do it here: blocked several people who constantly want to start fanwars, hate my fandom or my faves. If I don't see their threads, I will not be tempted to reply. If nobody replies, the thread sinks to the bottom quickly.
Love being in Kpop fandom a lot more since I started blocking everyone with bad intentions or hate.