First time playing a mage wondering what is best. I guess they all have upsides and downsides. Fire low cost, frost slows, and shock is fastest.

Fire has some prolonged burning damage too and shock saps magicka, but aside from that you know the rest.

The only other thing is that certain spells will be more or less effective against certain enemies e.g. fire will be less effective against a Fire Atronach but super effective against a Vampire.

I don't like how fire>shock>frost in terms of magicka cost. That is just stupid IMO. Not like it matters though since who uses magicka anymore? All mages should be abusing enchanting. I prefer shock, it travels the fastest of the three. Comes in handy when I'm sniping bandits with Chain Lightning.

Sounds like you got the basic idea. Also some enemies are weak to one of them and resistant to another, like undead weak to fire and resistant to frost. Very little is weak or resistant to shock, so it is best all round. Frost slows things down but there is lots and lots of stuff that resists it.

My favorite is fire cause I like burning stuff and fire does the most damage, especially with the aspect of terror perk, and there is not that much that resists fire. Just don't try to take down a fire atronach with fire. They are immune.

I think so i assume its not great idea to use my frost spells when doing the civil war quests against storm cloaks since your pretty much fighting nords 24/7 and they reset frost.

They all have their place. For me, fire is great for draining HP quickly and using fireball to attack groups at a distance. Frost slows down anyone trying to rush you and ice storm is great for close ranged groups. Lighting is what I use the most, because I want to, and its great for dealing with mages, dragons, and things with alot of HP due to with the perk they turn to dust at the last 15% of life. Its also the fastest moving spell and chain lighting can be used in the same fashion that fireball would be.

Well thats how I use them.

fire seems the most effective, most of what you fight is dragur or nords. Shock travels instantly so its easier to shoot things, like dragons, although i've never really gottten an npc mage to run out magicka by shocking them, so i wouldn't invest in it just for that