Some people say that "original is the best", but for me sometimes a covers can give a new color and -even- meaning to a song/music. I think original and covers is two things that can't be compared. It's on the same level.
Original is best because it's something new that people never thought before, so it's innovative.
-- while --
1. Covers is a work and an instrument for people to develop their creativity as far as possible.
These covers people can show the world how far their creativity to remake a song/music by their interpretation.
2. They also have challenges because re-make something that -obviously- most people already know is not as easy as you thought.
They must make it REAAALLY attractive and unique so it has it's own "charm" and people will remember it as their cover, not everyone else.
It's REALLY HARD when you re-make a work/music/song and you mustn't lose the essentials from it while you must show your own interpretation and NOT OVERSHADOWED by the original ones.
3. And don't forget that these people is also make their covers by their own perception, interpretation, and ideas -either as group or personal- so it can be considered as an "ORIGINAL", THEIR original.
In the end, it's all down to our own perspective. :)