Here are my Top five:
1. Strapping Young Lad/ Devin Townsend
I probably wouldn't have made it through high school if it wasn't for this man. His music could contain so much rage and frustration yet it could also be so melodic and beautiful. His releases are always consistently good, even when there are two or more a year. He seriously has more talent in his little toe than most people could ever dream of having.
2. Sigh
My first introduction to them was their 2001 magnum opus "Imaginary Sonicscape" which is probably the best album a 17-year old stoner could ever want. It's not even particularly metal, just keeping the black metal style vocals on top of psychedelic sweaty progressive dancey songs that sound like a drug fueled dance party hosted by Satan. It's also worth noting that their other albums all deliver the same crazy experiences, but Imaginary Sonicscape was just truly something unique that cannot be forgotten.
3. Killing Joke
I'm hesistent to include these guys because they're not exclusively metal, however their influence on both rock and metal from the '90's onward is monumental. They are criminally underrated and fit that niche where they appeal to people who want something heavy, but don't like metal. I have brought together many-a punk rocker and hard rocker fans with metal heads via this group. Seriously check out their '94 album Pandemonium if you want some industrial music that industrial metal bands like Fear Factory still cover.
4. Enslaved
Fast becoming one of my favorite bands, these Norweigian progressive black metalers put out one of the most amazing albums last year, Axioma Ethica Odini which kind of sounds like Pink Floyd if they made a black metal album. Over the last 11 years they have only gotten better at redefining a genre that is very traditional, yet without turning their backs on it completely. They're like the black sheep at the family reunion who everybody secretly envies because they were bold enough to do what they wanted and still find success.
5. Isis
One of the more prominent bands from the emerging "post-metal" genre which I'm determined to get people to accept as a real genre. Taking what Neurosis started in the mid '90's, Isis began to mix their brand of sludge metal with the atmospheric elements of post-rock and the drumming found in dub while adding lyrics heavily based around science. While Europe might be the best places for black and death metal, Isis helped make North America the epicenter of this intriguing new style of music.