Eh, there's some great stuff out there that uses harsh vocals (And some of it doesn't even go down the satanic route, but if you wanna generalize...). But if you're insisting on only clean vocals....
The Lord Weird Slough Feg (Straight-up, no frills, traditional heavy metal with a more contemporary sound)
Hammers of Misfortune (Prog Metal Supergroup that is <3 )
King Crimson (Seriously, why don't you have it?)
Manilla Road (Awesome heavy metal, no questions asked)
Psychotic Waltz (Again, awesome prog metal)
Megadeth (Not sure how big on thrash you are, but this is the best starting point along with metallica)
Thin Lizzy (Not really metal, but hugely influential to metal and Iron Maiden consider them to be one of their biggest influences
)