I'm actually surrpised Emperor has so many votes. Lord Belial 'kiss the goat(especially)' 'moonlight gate' 'unholy crusage', Sacramentum,Dissection > Emperor. Vassago Ex Lord Belial along with Anders from Sacrmantum are tremendous players especially. Necrophobic might not be pure BM but they're still a lot better than emperor also.
I recently heard Gorgoroth who are a lot better than Emperor. It seems emperor always get the attention. In The Nightside Eclipse is decent, nothing more. Emperor,Mayhem(besides De Mysteriis) are beyond overrated.