I had a conversation with a friend not too awful long ago regarding cover songs. We fairly well agreed that, with exceptions of course, most covers are not better than the original. Very few are even as good.
That being said, different and interesting covers get my attention. Not that they are better, just different. And interesting.
I stumbled upon 15-year old Gabbie Rae on YouTube doing some very interesting covers along with Patrick Kennison accompanying on guitar and backing vocals. I don't know much about either other than they make some interesting music together, taking songs of different genres and putting their own spin on them.
Here is a very stripped down acoustic version of Ronnie James Dio's "Rainbow in the Dark":
And here is a cool version of Michael Jackson's "Billie Jean":
They have also done covers ranging from Iron Maiden to Stevie Nicks to Curtis Mayfield