FUS - for dragons on the ground and I don't feel like getting singed or frostbitten
Marked For Death - for dragons that refuse to land (haven't gotten Dragonrend, yet)
Aura Whisper - the greatest shout for scouting dungeons, or finding what keeps detecting you when sneaking out on the tundra, all alone
Unrelenting Force because staggerin is helpful and it is fun to watch people fly
Dragonrend because I don't like my dragons airborn
Disarm on occasions because it is funny to watch people loose whatever they are weilding
Elemental Fury because with two daggers it is hilarious how fast you are.
Sometimes Whirlwind Sprint (mostly when I am carrying too much and trying to get to a store).
I have dabbled with throw voice, but it started hindering me when I would get into fights.
When I got to the part where you fight Mercer Frey (I believe that was his name) face to face, I thought "Prepare to get knocked back" as I pressed the dragon shout, let it fully charge up, and then... "Hey cheese brain". Mercer promptly cut me afterwards.
Unrelenting Force: Great in combat when I need a window to whittle down a tough enemy's health, and just for comedy effect. It's also equally useful and hilarious when I'm fighting a Forsworn (it's always them!) near a cliff and they won't take a hint.
Whirlwind Spirit: Sprinting isn't fast enough! Also a good way to get past traps in dungeons.
Call Dragon: I never really need to use it but I do anyway because it's awesome to be able to do it.
Call of Valor: Outnumbered? Instant follower! His Unrelenting Force come in useful too.
Dragonred: The most annoying thing about fighting dragons is waiting for them to land, so this is useful for saving time.
I occasionally use other shouts when the situation calls for it, like Become Ethereal when Whirlwind Spirit doesn't work on certain traps; Clear Skies when it becomes cloudy and I can't see in the distance when I want; Fire and Frost Breath when I want to mix up combat a bit (never worth it really); and Ice Form for teh lulz, and it also works like Unrelenting Force in battle, although I find it's not as effective.
FUS RO DAH! and marked for death, it makes it easier to take people on head on and easier to take on groups with melee.
oh and dragonrend because i hate it when dragons fly around all like "look at me, i can fly" and ignore me when i want to kill them (unless it's an ancient dragon then i run away weeping like a little girl.
What irritates me about the shouts is seeing someone else studied in the way of the voice (namely the greybeards) and their cooldown is near instant. Whereas me, the dragonborn, have to wait. Making a lot of it effectively useless.
I mostly use Unrelenting Force, for throwing enemies off cliffs.
Whirlwind Sprint just to run through traps quickly and to just explore places.
Dragonrend to bring down the dragons.
I occasionally use the fire breath one.
I used to be in the crowd that only uses Unrelenting Force, but then I discovered that... Ice Form, was it? The one that pretty much freezes a target solid? Great way to have fun when you're taking on a big baddy one on one. Met a frost troll once, on a tall mountain. I was nowhere near the level to take on a frost troll, and I sort of... Well, I panicked. I thought I had Unrelenting Force equipped, but I was mistaken. The troll charged at me as I launched my shout, and to my surprise the bugger froze solid and kept going in it's original charging direction, right past me and off a cliff.
Gotta say, I hate it when I have those moments and nobody's around to witness it. I can imagine what it must've looked like down below, a frozen frost troll falling from the sky.