The kind that is good. No seriously, that is literally my one and only criteria for whether or not I will in fact listen to something. It wouldn't be stretching the truth much to suggest that I have a particular penchant for Hard Rock and/or Metal though, and the way my mind functions, I probably don't actually consider the music I listen to that folks would classify as "Rock" to actually be Rock, as I tend to reserve that label for music closer to Hard Rock than anything else, but ultimately I only care if it is good.
So considering the crap that floods our modern airwaves, you could say that I'm a very selective listener - good Rock is in short supply unless you are willing to dig.
So considering the crap that floods our modern airwaves, you could say that I'm a very selective listener - good Rock is in short supply unless you are willing to dig.