Because i can't pick one, here's my top 3:
Amorphis
Their sound has aged really well from melodic doom to progressive / melodeath. Tomi Joutsen has absolutely breathtaking vocals, from clean to brutal growls.
Their performance of Black Winter Day is my all-time favourite footage of them live.
Favourite Albums: [Skyforger](Amorphis - Skyforger (full album: http://www.youtube.com/playlist?list=PLjojBqb6z6ByY9v8enHwYxbv1h2MrHaDx) and [Under the Red Cloud[(Amorphis ''UNDER THE RED CLOUD'' [2015]: http://www.youtube.com/playlist?list=PLSZ-RAt8RyYrkLg37DE9QpmrAkbi1EksP)
Korpiklaani
These guys know how to party and drink.
These guys are and always will be my favourite pagan folk metal band. From their newer, more festive songs like Vodka, a Man With a Plan(I prefer the finnish version, Viinamäen Mies) and [Pilli on Pajusta Tehty[(https://youtu.be/lCGlO2Ssqwk), to the heavier ones, like Väkirauta.
The Violin and accordion really mix together very well ( As heard in a man with a plan ). Their live shows are really good sounding and entertaining ( The lead singer Jonne has poured vodka into the mouths of people frontstage ), the crowd also usually works really well with line-dancing and moshing.
Favourite albums: Ukon Wacka and [Manala](Korpiklaani Manala: http://www.youtube.com/playlist?list=PLDYt8WJqfgCGuW9meZG3lm_a1dj9ZGJQs).
Cannibal Corpse
Holy fucking shit are they brutal and heavy.
I do not like Chris Barnes' vocals that much ( Well except for in Stripped, Raped and Strangled ). George Fisher really is amazing ( just look at thst neck of his ), his vocals blow me away everytime, even if he has a hard time singing the lyrics properly live.
Also, just take a look at their album covers
Their lyrics are basically a gory horror b-movie condensed into one song.
All of the band members have definately mastered their instruments and stage presence, especially the bassist, Alex Webster.
Just look at a guitar cover of Frantic Disembowelment. Jesus Christ.
Favourite songs: Hammer Smashed Face, Evisceration Plague and Priests of Sodom.
Lordi is a honourable mention.