I like almost everything from the Alteration School.
I wish we could use Teleknesis on people. That would have been amazing. Those darn PC players have that I'm sure.
Aside from obvious Restoration, I like Transmute in Alteration for money, Frenzy and Invisibility in Illusion, and all Conjuration magic.
Now there are two words that definitely go together for me. I go for Grand healing in the same way I aimed for Cure Disease in Oblivion: my characters aren't serious contenders as adventurers until these have been learned.
Spells are.....well i got depressed really.
I worked my behind on one of my Characters, wanted to do everything 100% legit. So when i finally hit enchanting 90, i had some fortify enchanting potions and was able to have 4 pieces to reduce magicka by 100% (25% per piece).
So, i was shocked to discover, that the master spells (for all schools) have a very long animation, where any enemy nearby can and will interrupt you with a power attack or even an iron arrow.
No, you can not use become etheral, because some spells bug out such as blizzard and no, not all spells can be done through walls and objects.
Only Conjuration is worth it, i got so sick of the animation and being interrupted, i hit legendary in all school (which is a joke, since 3 master destruction spells got me up from 15 to 74 or so, so you can spam magic like mad).
Fireballs and Summon Dremora.
Come on, who wouldn't want to throw freaking fireballs.
I would use Fireballs more often if they didn't knock everything from it's place. It becomes a pain in the ass searching for gems and potions.
The mage light spell you shoot (not the hover-over-your-head one) is pretty cool. Beyond that and healing spells I don't really like any of them one way or the other. Had there been shapeshifting spells... well, then I'd be playing a mage hybrid and in absolute love with Beth for putting those spells in. They didn't though, sadly.
Shapeshifting spells for TES6!
My favorite spells... let's see:
Incinerate, Thunderbolt, Icy Spear, Firestorm, Lightning Storm, Fire/Frost/Lightning Cloaks & Walls, Dragonhide, Paralyze, Mayhem, Harmony, Calm, Frenzy, Circle of Protection, Fire/Frost/Storm Atronachs, and since I tend to reuse the Deathlords I kill lately, Dread Zombie
I don't use Magic..
Just a Bow and Dagger for me thanks
my altmer pure mage: summon atronach, chain lightning
my orc 2-hand tank: slow time (shout)
my dunmer assassin: vampire sight (power)
Fireball Fireball Fireball all day.
Ice spike is fun too, I like the way frost spell look in your hands as well.
Im on PC and dont have a clue how to go about modding, so Im just gonna leave it until I beat the whole game Vanilla + DLC's and HD Package. The whole reason I would mod is to increase play time and to keep the story going.
On topic, my favorite spell has to be the Ritual Stone ability, I have raised over 20 dead NPCs before using that ability, and then add fortify onjuration potions, and you have a mini army for 10 minutes.