To be honest, with the exception of Mikael's stylish prose, a lot of the lyrics of our favourite Swedish metal bands are crap. In Flames's lyrics are terrible, and as much as I utterly worship Dan Swano, he's not the greatest lyricist. Some are pretty good, others not so great.
Overall, once again Frank Zappa would be my obvious pick, in all his ...variety, with props to Lennon/McCartney, and Paul Simon, specifically for "The Sound of Silence".
And hell, you gotta love the occaisonal Slayer lyric:
"Enticing Malevolence allures
Bastardize the clean and pure
Salvation forever cruxified
I choose the othe side oh yea
Entire, complete serenity
Injected intravenously
Transgression euphoric bliss devine,
initiate a timeless stain of mind...
blood will sterilize
in fire baptized
all pain sifts through my soul
you'll never feel greater misery
master of my enemy
let the purest stain of mind
wash the virtue from your eyes"
perhaps I just enjoy screaming along with that. Anyhoo...