通常陌生人之间不会用”什么事？“，给别人的感觉你正在忙，并且不耐烦，Sounds like”It not a good time“ 通常可以说： 有事么？ 怎么了？ But如果两个人关系很好，就无所谓了。

I would say the following, never thought there were so many ways to respond, 什么事？ 干什么？ 怎么的？ 干啥？ 有事儿？ 啊？ 哎！ 在这儿！

就我而言，什么事，干嘛，啊 用的比较多

I like to say :啊

I'd like to say it depends on different situation when people call your name.say,you people who speak English will response it sometimes with Whats up,so we also usually say 怎么了 and 干嘛(it's casual),also if it happens between friends,we definitely always respond with啊? But sometimes when people call you in formal way,like, checking attendance,you know the response will be. formal ,, too. all in all,just be appropriate will be fun! have a good day