a lot of it is a bit sickening.
stick to the dischord records catalog and you can't go wrong.
i find the terms 'emo' and 'post hardcore' really broad when used as descriptive terms to link bands to a genre.
like some people call Fugazi post hardcore, which kinda makes sense, and some people call that crazy metallic off beat weird time signature screaming stuff 'post hardcore'. which doesn't sound like Fugazi at all.
basically, when it comes to that sort of thing, i think it takes a lot of sorting wheat from chaff and im not prepared to do it.
check out Embrace (the dischord band) maybe Dag Nasty, Swiz, Fugazi, Jawbreaker, Samiam, Quicksand, Rival Schools, Lion Of Judah, Jets To Brazil, American Football (awesome guitar work!), Cap'n Jazz.
though i guess a lot of that verges towards hardcore.
f*ck Ateryu and Grade and stuff like that.