You can't just outright say one musician is better than another, it's entirely subjective. Eminem and Justin Bieber appeal to completely different audiences, use completely different styles and have completely different meanings.
I personally love Eminem and don't necessarily care about Justin Bieber, but just liking Eminem more doesn't give me the right to claim that he's better.
It most certainly does.
While I'm not endorsing the OP (I think his actions were silly), you can't say that taste is subjective, and then turn turn around and say that "Just because you don't like them doesn't make them bad."
Yes, yes it does. And it does by exactly what you just said.
Taste is subjective. Therefore, the Great Arbiter of Taste is none other than yourself. All you can ask of another person is to realize that they are their own Arbiter of Truth, not mine.
The Meaning of Life, the Universe, and Everything.
Personally, I think Eminem is alright. I listen to his music every once in a while, but I don't listen to him 24/7.
As for Beiber, I don't really think much about him anymore. The guy pretty much had a couple big songs, then went full jerk.
Just my thought on this topic: honestly, I hate when people do these types of posts/topics. So and so is better than this and here are reasons that I think are true. It has no actual proof that this person is better than the other. As stated before, it all matters on the genre of music you listen to. Everyone is entitled to their own opinions. Keep this in mind before you start these topics.
I'm not a fan of the rap genre, but I can appreciate that Eminem is an exceptional lyricist at times (eg Lose Yourself, the complexity of his rhythm and his rhyming far surpasses what you'd expect). Justin Beiber on the other hand... Can't really say much positive (except maybe he at least can play instruments I think?).
"Critics who treat adult as a term of approval, instead of as a merely descriptive term, cannot be adult themselves. To be concerned about being grown up, to admire the grown up because it is grown up, to blush at the suspicion of being childish; these things are the marks of childhood and adolescence." C. S. Lewis