ESA, I've heard a lot about Norther but never really tried to listen after I discovered a few "bad" songs from them. Could you eventually recommend me some "less-known" songs that you consider close to COB's?
Hard to actually come up with a song that would sound "like" COB in that one might be fooled it was made by COB, but Norther has always mirrored COB with their own style IMO. Just like COB the first few albums are very melodic, and, as COB began to lose their melodies and go into a more thrash oriented style, so did Norther.
As for recommending song by them?
The "well-known hits" are, I guess:
Mirror of Madness (This one got me listening to them)
Death Unlimited (I really like the attitude in the vocals, otherwise the song isn't quite worthy of it's fame IMO)
Frozen Angel (Not a big fan of this song personally)
We Rock
My personal favorites would be something like this (Divided by album (And though the albums are in release order, they also happen to be in quality order; the first one is the best one, the last one is the worst one (Though I skipped their 4th and 6th albums entirely))):
Darkest Time
Released
Endless War
Victorious One
Blackhearted
Betrayed
Midnight Walker
Mirror of Madness
Deep Inside
Death Unlimited
Hollow
Going Nowhere
Saviour
We Rock
C.U.S.
Dreams of Endless War is definitely one of my favorite MDM albums ever, possibly even eclipsing FTR in that regard. Instrumentally it's hard to say which band I prefer but I really love Petri's lyrics most of the time, they are so freaking angry and "badass"