I feel everything's important but I do put emphasis on the lyrics and vocals in general, yea. I like many bands that sing in languages I cannot understand; it's generally metal (or sub-genres of sorts) though, because mostly if the instrumental work is good and the vocals complement it I can enjoy it either way, German, Swedish, Finnish, Gaulish, French, Amernian, etc.
Depressing lyrics, so to speak, tend to bother me a lot. I won't say "emo" but lots of metalcore bands the likes of August Burns Red, As I Lay Dying, My Dying Bride, newer Linkin Park/Lost Prophets/etc. have really, really bad and repetitive lyrics (from my personal, very limited knowledge), they just talk about teen angst, problems with a society that seemingly refuses to accept them for who they are, not wanting to live in a world like this, etc. Killswitch Engage, on the other hand, I have no problem with, they have great songs and their lyrics are certainly not terrible. They're still pretty much strictly metalcore.
Note I don't mind depressing songs, though, Elliott Smith was extremely talented and 99% of his songs deal with (getting over) depression and our everyday problems, many other well known artists of many different genres like Tom Waits, Everlast, Johnny Cash, Deep Purple and tons of others. I really like these songs. I guess the way the metalcore/screamo bands sing theirs and the themes they deal with just don't seem remotely honest or heartfelt, if you will, compared to all these.
There's lots of genres you can branch out to if you like heavy instrumental work with cleaner vocals; anywhere from random Industrial bands to stuff like Devin Townsend and Porcupine Tree like Kerath mentioned, Opeth. Thrash like Anthrax, Kreator, Mastodon, Meshuggah, I don't know, Folk and similar "mixed" genres if you're into that sort of thing.
I linked Introspection by Ihsahn (from Emperor) which is actually with Devin doing back-up vocals. I absolutely agree, his music is ridiculous (lots of it in the literal sense even) and Addicted is a great album. I personally really love Ocean Machine, every song there is amazing. Terria's good too and I feel it's quite underrated because none of its songs are remarkable by themselves, it's just really absorbing and introspective as he put it.
His albums with Strapping are fantastic too but it's a completely different thing. City, Alien, New Black etc. are all top notch.
Porcupine Tree are so very consistent. I don't think they have a single bad song, I don't know if I've listened to all of them but I believe I have at one point or another in time and I can't recall a bad track. Their newer record actually sounds a bit like some of Opeth's mellower tracks (both old and new) but that's certainly not a bad thing - their music in general is not really my type but it's impossible to dislike a band like them.
inb4