Considering the response to this thread so far I'm not sure anyone actually wants a serious response but I will take the chance to shill my oshi a little.
First of all she's just legitimately very funny. She has a good sense of timing and restraint for pranks or poking fun at people to make it entertaining instead of just cruel and she's got the right attitude to be on the receiving end of it to. But also just her general mannerisms and choice of wording when talking are amusing, she often phrases things in very strange ways and then just acts like it was totally normal. Plus her tendency to get distracted into endless tangents.
She also reads and responds to chat a lot which helps keep that banter feeling going, it's part of why her superchat readings are always so long because she spends most of the time not even looking at the superchats and just sort of chatting with everyone.
Also her laugh when she's really happy and enthusiastic about something is super cute. For what it's worth she's not really that much of a brat, she's super shy and respectful to basically everyone except her closest friends and her teasing is not the slightest bit malicious