Isn't symphonic metal also one of the subgenres of heavy metal.
One the better symphonic albums in recent time are from Xandria. Bands like Nightwish, Epica and Within Temptation are also pretty badass.
Anyway its still a great list of heavy metal music and a showing of how varied metal is. I like heavy, symphonic and progressive metal the most. Pirate metal like alestorm is also likable for me.
Please excuse my (probally) poor grammar