Well, I can't decide on my favorite metal-producing country, so I'll list 4.
1. Sweden: Vintersorg, Opeth, Dark Funeral, etc.
2. Norway: Borknagar, Dimmu Borgir, Limbonic Art, Dark Throne, Myrkskog
3. Finland: Amorphis, Stratovarius, Sonata Arctica, Obscurant
4. US: Seven Witches, Death...