Well this is a conversation that could go on for hours honestly....in general I'm not a fan of covers. I tend to only appreciate covers when a band does something different with the song, sadly most don't. Take the new cover of "Africa"...what a waste of talent...it's literally the same as the original, so why bother..
I prefer when a band like Marilyn Manson does a cover and just throws a wrench in the mix and builds a new bridge completely.