You'll want to grab the apotheosis staff as soon as possible since it hits with 33 damage each of frost shock and fire which is pretty devastating against most enemies. The nice thing about staves is they completely ignore that spell effectiveness penalty from wearing armor, so you can deck yourself out in heavy gear without worrying about magic penalties.

Through the mages guild questline, you'll get access to some really good options and you can actually pick between different effects like destruction illusion or mysticism. The staff of paralysis is particularly useful, freezing enemies for 8 seconds without draining any of your magicka which is great for crowd control.

Just remember to keep some soul gems handy since staves need recharging but honestly, the damage output is worth the maintenance especially early on when your regular spells aren't that strong yet. The triple damage from apotheosis really shines against enemies with single element resistances, and having a paralysis staff as backup lets you control the battlefield pretty effectively.