Really, all of their albums, Broken Base aside. Emperor was an astonishingly consistent band.
The ending of "Inno a Satana" from their performance at Wacken 2014. Ihsahn and live keyboardist/vocalist Einar Solberg perform a vocal harmony where Einar ends up pulling off a superb type 4 Metal Scream.
Better yet: Which album is better?: In the Nightside Eclipse or Anthems to the Welkin at Dusk?
It doesn't help that many fans feel uncomfortable about aspects of the band's past. Both Samoth and Faust have both done prison time at some point or another, Faust having done his for murdering a gay man which he still has no real remorse about and Samoth having been involved in one of the Norwegian church burnings. Ihsahn also expressed Social Darwinist views in interviews, claimed that Christianity was a religion for weak people and even justified the Norwegian church burnings (although this last has been subject to Flip-Flop of God as at other times he's condemned them). Ihsahn however seemed to have dwindled down with these views, especially now in regards to his criticisms towards the Norwegian church burnings, as well as pointing out Euronymous was a rather negative threat to the community with his death threats. Ironically enough, Euronymous wrote the riff for "Ye Entrancemperium" and In the Nightside Eclipse was dedicated to him.
Epic Riff: Lots of them. The main riff of "Ye Entrancemperium" stands out, though, which shouldn't be a surprise since it was composed by Euronymous.
Even Better Sequel: The more Progressive Metal oriented section of the band's fanbase feel that Prometheus is their best work. Some fans also prefer Anthems due to the more polished sound.
In the Nightside Eclipse is hailed as a classic. Anthems to the Welkin at Dusk? Even more so.
Tough Act to Follow: Some believed this was the reason Zyklon wasn't a worthy successor, despite both being very different. Ihsahn's solo work also gets this to some extent, though arguably not as much - it's quite acclaimed in Progressive Metal circles, particularly The Adversary and After.