Lemme get this straight: Favoritism is very subjective.
Bleach Movie 3 - Fade to Black
OST - Fade to Black Irish Dance
This excites me to high heaven.
Fullmetal Alchemist Brotherhood
OST 2 - Xing Symphony ~Overture~
Because character introductions with this playing in the background is just :ahn:
OST 3 - The Way of a Ninja
Feels. Unless you're one of the White Zetsus.
OST 1 - Shippuuden
A suspense-building hype-inducing most-definitely-for-fight-scenes kind-of music.
OST 1 - L's Theme
I like this one so much because it also fits in as a Sherlock-esque theme. Thought provoking at first, and then the upbeat just kinda forces a decision. That's how I interpret this. Let's not forget L's Theme B:
OST 1 - L's Theme B
This reminds me somehow of the Red Hot Chili Pepper's Snow, from Stadium Arcadium. Weird. But awesome.
I shall add more as the rest rise up from my subconscious.
But pleeaseee feel free to suggest, as I am also building an anime OST collection ^^