First a little question for ya: why are you here?
Why are ya here on this board?
You admitted that you don't know any material of 'em(okay, I can live with it 'cuz you were honest), so it just confuses me.
There is no first album(k, perhaps Vs the World), get them all
Every LP is a bit different, but still has the typical AA sound/feeling.
I would recommend the first (Once Sent From the Golden Hall) or the most recent (Vs. the World). The Avenger and The Crusher kick ass too, so it doesn't matter too much.
Like the man said, just go buy them all. They all kick ass, not to mention give ya a bit of whiplash if you listen to them too much.(Is that possible?)