Mine are in order:
1. Marked for death
2. Elemental Fury
3. Disarm

4. Slow Time

5. Kyne's peace

I'm roleplaying a werewolf/warrior, so I can't get the third word of marked for death, but even with two words it's easily the best shout in the game. Using it just once makes my axe cut through even the toughest enemies like butter.

When in traffic I like shouting: "Go f*&^ yourself."

For Skyrim it just depends on the character.

So many to pick from... unrelenting force (especially for knocking people from altitude)

Elemental Fury (with dual daggers - WEEEEEE!!)

Fire Breath (just because)

Whatever the detect life one is called.

I like the idea of the Fear and Disarm ones, but they seem so ineffective. Given the recharge time of a shout, I'd rather go for something with a guaranteed effect then a potential effect.

I also really liked the idea of the storm calling shout, but its useless if you've got a follower.

"SHUT THE UP!!!!"

In game: Marked for Death.