Hahaha
This thread is two topics below a clone thread, but now it's on top of it because I commented.
I'll have to go with Iron Maiden, though there are close runner-ups. It usually depends on my mood, but I can almost always be in the mood for one Iron Maiden song or another (unless it's from their newest album - bleh).
The Beach Boys, Blind Guardian, Gorillaz, Great White, Motorhead, and The Rasmus are close runner-ups.