I heard Dremoras are better but wouldn't storm atronachs be good if Im a melee character?

Dremora Lords > Everything

Well, they're both daedra, but dremora lords pack a punch.

Advantages of Atronachs? Ranged combat, they stick around as long as you need them. They self heal. Storm atronachs are the most fun and are great for dragon battles.

Dremora Lord pretty much outmatches every possible follower or being you could conjure.

Atronachs at first, and when you're a high enough level and have enough magicka, then the Dremora Lords take over.

Mix it up, dremora lord for up close and storm atronach for range.

I would suggest dremora lord unless you haven't got dragonrend for fight with dragon.

Even with legendary dragon they are still a very viable option.