Dont know if youve been to teh College but if you do some quests for Arniel you'll end the quest by getting the conjure spell Arniels Shade. I think he is better than Lucien the Dark Brotherhood ghost and you can use him anytime AND it cost 0 magic points.
I use Werewolf here and there for when i loot to much or when i wanna kill some bandits badass style lol.
dont need to use calm since im a mast illusionist i can pacify Giants, Bears easily
but the shout i use the most is Become Ethereal. When i need to jump off a cliff or mountain i gotta use it and i jump off high stuff alot. After that unrelenting force cuz its powerful and recharges fast and last Flame breath just cuz my Legendary Daedre sword is enchanted with fire.
fave shout is Storm Call for sure though. I freaking feel like a Dragonborn when i can start a massive lightning storm. Call a Dragon is cool too lol.