Most bands do not hit me right away. Three of my current favorite bands (Marillion, Porcupine Tree, Riverside) didn't have anything that *INSTANTLY* nailed me to the wall.
I've only had THAT experience twice that I can remember since 2000.
Used - Pain of Salvation
Welcome Home - Coheed and Cambria
In each of these cases, I was INSTANTLY floored, and knew that I had to own that CD *RIGHT THIS SECOND*...
Those songs still amaze me. Even though there are so many songs from PoS that I like even more....Used was the one that really made my jaw drop within the first minute. Even Welcome Home took me until the first chorus.... So really, NOTHING has hit me harder than Used in a very, very long time.