I treat my #/10 more like an analysis of how good or bad it is with something like how much I will or will want to listen to it. A 10/10 is a song that is essentially perfect and could not have been created by any other band and has almost no flaws, or at very worst has no major flaws (like one instrument, say drums or bass, that is a lame duck, but not in an intrusive way). A 9/10 is a song that is about as talented, well arranged, or broad and sweeping, just a bit more flawed. An 8/10 is a song that I like and could listen to tons of times, and usually do. A 7/10 is a song that I like that has too many flaws to listen to tons of times. A 6/10 is a 7/10 that does not excite me at all for whatever reason, and also the cutoff for where I stop considering songs below, since everything below is either basically mediocre relative to great music, actually terrible, or only has maybe 1-2 good instruments with something else horrible. For instance, something like a bad 'disco beat' will destroy nearly any song; only the greatest bands could still make good music through that. My biggest emphasis, since music is so hard to accurately judge, is pretty clearly on flaws (though excitement/delight is factored in a bit on all levels above a 6/10).
I really don't much care for a rating system that is based a lot on flaws in the music. I really like music for how much excitement it evokes from me when I listen to it. When I rate songs, it's usually entirely on the basis of how I feel when I listen to it. Anything below like a 4 gets that way because I am listening to it and can't even immerse myself in the beat or the music, because it's really too much. That's why I really can't get into metalcore or black metal, because regardless of how technically precise they may be, the music has no affect on me. Below like a 2/10 rating is because it does have an affect on me, but that affect is nausea. A lot of pop music does that to me, so I stay out.
I think that a lot of that intense metal has so much sound because they are trying to express their rage? (correct me if I'm wrong) but there are other bands that can express their rage without a wall of distortion; Rage Against the Machine is my favorite example. They have all these crazy riffs and stuff, but the singer expresses the rage perfectly by going crazy. Like in Freedom, Bullet in the Head, and Wake Up, there's a section where they just start slow, and crescendo massively while Zach yells a lot. But they don't have to compromise their music by cranking up the distortion to max and using double kick bass pedals every note. They still play with a lot of energy, and that energy gets to me when I'm listening to their music, so I can't just sit around and throw up the horns or something, I feel a physical need to get up and go wild alongside the music. It's like a feeling in my lungs and stomach, and when I get that feeling, that's when I want to rank a song 9/10 or 10/10.
Anyway my favorite bands
Black Sabbath - A lot of you guys like metal, this is where metal really started, unless you want to say that zep and cream and iron butterfly started it, which I don't see (I mean, I like those dudes a lot, but they aren't metal). Black Sabbath came down with some of the greatest music and riffs of all time, and the first time I heard them was when I decided that I wanted to start listening to music. I overplayed the albums I had by them, but they were good enough that I didn't even mind, I would listen to their stuff three times a day and never get tired of it, and I've matured a lot since then, but I still don't tire of Black Sabbath. (take note glen when a band takes hold of you with that much power they don't really let go)
as a matter of fact np black sabbath - into the void YEAAAAAAAAAAAAAA
Rage Against the Machine - really I think I already explained them. Monstrous riffs etc they kick ass
Blues Traveler - Okay this is kind of different from the other two bands but come on Blues Traveler is fantastic. The first live concert I went to was a Blues Traveler concert, and I don't know if that had a huge affect on me or what, but these guys are fantastic with their hard rock sound and long jam sessions. They're pretty great musicians, and they can do some great songs with major keys, minor keys, lyric heavy songs, instrumentals, or my favorite by them "Crash Burn" which has the coolest instrumental section ever (basically trading off between guitar, harmonica, bass, and drum solos).
Metallica - Pretty much everything that happened Kill 'Em All - Black is fantastic metal stuff. I usually try to understand why music makes itself so appealing to me, but I can't figure it out for Metallica. This isn't to say that it's bad, because it's fantastic stuff, but I originally didn't care much for them, but after listening to them for a while, they just grew on me and I found myself even lusting after the filler tracks on Ride the Lightening and Master of Puppets.
Led Zeppelin - Jimmy Page's songwriting is great. I get bored with some music sometimes because a lot of stuff is intro-verse-chorus-bridge-chorus-outro or some variation, but zep did a lot of stuff, especially in their early albums, that didn't conform to that. This isn't to say that they didn't write songs like that (communication breakdown is still good ok) but some of their best songs were stuff like the Lemon Song, Good Times Bad Times, Dazed and Confused, Moby Dick, etc. I think I was stupefied when I first saw a live video of Dazed and Confused, when Page whipped out the violin bow and they played that song for at least 45 minutes.