Sworn to the Black > all
EDIT: Here's the objectively correct Covenant hierarchy
Sworn to the Black - 4/5 (the worst flange abuse, but there's one really excellent riff in here as well as amazing leads that lift this to a 4, the arrangement is actually good as well)
Nar Mattaru/God of Emptiness - 2.5/5, 4/5 (former a cheesy spoopy synth intro) (maybe it's familiarity with Morbid Angel's Top 40 Pop Hit, but the downtuning feels more natural here, nice and lurching, the melodic change around 2 minutes is very powerful)
Angel of Disease - 3.5/5 (lol so out of place, the leads are an improvement, the flange is a downgrade, overall about as good as the original I guess)
Lion's Den - 3.5/5 (the Middle-Eastern riff-unit is nice but as with the rest it doesn't lead into anything interesting, the 1:45 tremolo-picked part is good but fleeting as usual, I guess this one does feel like it has a consistent rising tension though, fading riff was cool too, almost Ripping Corpse-esque)
World of Shit (The Promised Land) - 2.5/5 (almost obnoxious how downtuned this sounds after the first two songs, after the sludgy part it alternates between a basic thrash riff and blasting parts)
Pain Divine - 2.5/5
Vengeance is Mine - 2/5 (there are parts that almost sound genuinely tense on their own, but the whole formula on this album is so tiring, just an overglorified later-Lombardo Slayer song with added blasting)
Rapture - 2/5 (super boring riffs and structure, flange, decent break around 2:20)
Blood on my Hands - 1.5/5 (downtuning again, cookie-cutter riffs, goes nowhere)