Ppl seem to have different views of what's metal and what's not. Some say hard rock bands like AC/DC and Guns N Roses are and some say not. I really don't know about AC/DC besides a few songs, but GnR are metal in my opinion. Not the heaviest, but they have the hair metal sound similar to Ratt, Whitesnake, Stryper, and the Scorpions.
I still listen to Nu Metal, I also hear that a lot of metal elitist don't consider Nu Metal as real metal, I know a few who also don't consider Metalcore as real metal. I consider them both as metal. I use to be extremely crazy about KoRn. I still like them, but not as much as I did in 2005. Their older stuff (when they had Brian Head Welch and David Silveria) sounds better to me and I like their albums like 'The Untouchables' and 'Issues'. Their new stuff is good as well. I am not sure if I will like the dubstep stuff, I like dubstep to an extent, but after a hour of listening to dubstep, it begins to give me a headache. I do like Skrillex though. As far other Nu Metal bands, I like P.O.D., Slipknot, Ill Nino, Blindspott, Sevendust, Disturbed, Linkin Park, some of Limp Bizkit, I.C.P. (I am not a Juggalo, but I do like some of their songs), Skindred, Lostprophets, and a few others.
