I love Skyrim, I am the Brian Blessed of Skyrim.
Call Dragon - Haven't got it to work so far, guess it's busy doing other dragony things, the ironing or whatever.
how far along are you on the main quest?
as for me the ones i like were marked for death for my assassin versing dragons or bosses or when i just plain up and fail at sneaking

also like unrelenting force because i like watching things fly off cliffs
then there's ethereal which is fun for jumping off high places
ice form i use occasionally
i use call dragon and/or storm when im raiding a fortress and have to kill a bunch of dudes out in the open
aura whisper was occasionally useful for my assassin for sneaking around without being detected or just getting in a good spot to backstab someone
slow time is useful for my mage because some guys just move too fast for me to get a good hit in while thy are moving and they seem to be constantly moving, like the priestys, so it slows them down so i can aim better and maybe stagger them.
call of valor, not much use for my because i already have lydia or whatever follower i end up getting after she dies
throw voice was never needed because my assassin was pretty good at sneaking
whirlwind sprint was good just for time saving, when i didnt inadvertently shout myself over an edge of course.
clear skies helps when the weather is just getting annoying
never used animal allegiance, kyne's peace, fire/frost breath, disarm, dismay, or elemental fury yet.