They're both great albums, but my personal favorite is Seven Swans. I think its a perfect record.
I could see why you'd pick Seven Swans it's bad ass. I remember Sufjan saying that he wanted to make an album for each state. Here's a review for Illinois written by a friend. Not sure he'll get to all 50.
I often forget how important a first line of an album is, that's a good one. They always say how important first impressions are in life, why should music be any different? That'd make a good post "best first lyric". I've always been a fan of Put your hand on the wheel, let the golden age begin
For best first lyric I'd probably go with Van Morrison - If I ventured in the slipstream / Between the viaducts of your dream / Where immobile steel rims crack / And the ditch in the back roads stop / Could you find me?
It's a good one. Was it you that mentioned this album a couple weeks ago in a comment? It's a good one.