What should I report BM players for?

So I just got done playing a ranked game and was wondering what I should report BM players for, as in, what category. I don't usually report people for spamming laugh or stuff like that, but the enemy team's Malphite was probably the most BM player I have ever met since starting league of legends. He said "GG EZ" when they first blooded us with an invade and kept repeating it every time they would get a kill along with spamming emotes. That and other stuff he said really got on my and my team's nerves and made me sincerely wanna win just to shut him up even though I'm not the incredibly try-hard type. We were pretty behind at first, but then we all muted him and started making a come back and came pretty close to winning. Unfortunately our ADC getting caught and me trying to save him and instead dying with him made us lose in the end. Needless to say we were all pretty salty and 5x reported him. I myself reported him for negative attitude along with mentioning in the details that he was BMAF. Was that the right category for the report ? P.S. Sorry for long post but I just wanted to get this off my chest and see if any of you guys can relate to such a story.
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