This is the stuff that appeals to me personally most intensely.
Heroin - self-titled 12" EP / discography CD [Gravity Records, 1992?]. This record is the end-all, be-all of emo for me. A wall of furious, chaotic noise, vocal-cord-shredding screaming, lyrics of ultimate disillusionment and pain, just the right amount of melody to pull things together without interrupting the flow of angst. The 12" is a perfectly constructed 20-minute epic of emotional disaster. The 2nd 7" that preceded it is historic for its vocal brutality and unrelenting guitar attack.
Reach Out 7" and split 7" with Honeywell. Thick, heavy, chaotic hardcore with an anthematic, epic feel.
Swing Kids - discography CD or 7" [31G Records]. Hard to sum up in a few sentences. The first track on the 7" is still probably the best single example from this style, heavy and gut-wrenching yet brilliantly musical. In my opinion this was Justin Pearson (Struggle, Locust, etc) at his very finest.
Portraits of Past - split 7" with Bleed [Ebullition]. This was a shock when it came out. The vocals on these two songs stand today as some of the most extreme hair-raising screams ever put to tape. Musically, this and the Reach Out stuff define the Northern California hardcore sound.
all Mohinder (two 7"s and a split 7" with the Nitwits). A deeply melodic hardcore band with basslines that twisted all around your skull, these songs were gems boiled down to one or two minute epics.
Merel LP/CD discography [Gern Blandsten]. Crazy chaos held together by a swirl of oddball looping riffs.
Antioch Arrow - In Love With Jetts LP or CD discography [Gravity]. Chaotic hardcore at its extreme. Nonsensical music somehow rhythmless and tight at the same time. Widely dismissed as fluff at the time for the lack of content perhaps, but these records stand well on their own.
Angel Hair - 7", LP / discography CD [all Gravity Records]. More taut and composed, starting to branch out into more adventuresome music like a Bauhaus cover. Still chaotic and heavy.
Guyver-1 7" - a little later in the game, but fantastically good hardcore.