Everyone has his favorite idea of a character I think, personally when I play a new Elderscrolls game my first character is nearly always like the following. A Female breton who uses the heaviest armor possible, maces, shields and casts restoration and alteration spells alongside a bit of destruction spells. Basically I go for as much durability as possible, A ton of armor with magical defences and a healing spell running, not to mention magical defences as a breton and the race ability shield, I go either for the mage or the attronach depending on what I feel like trying, I went for mage for first time I plaid in both Morrowind and Oblivion but I′ve plaid through Oblivion another time with the same kind of character with the Atronach birthsign.
I don′t care about my ability to sneak, I waltz right through things if possible, and I don′t care about my damage, my hits can feel like a kittens paw to that Daedra I′m fighting, just as long as his hits feel the same to me
You could say since I get armor with reflect damage that I′m like a rock that heals itself but can′t do much damage just rolling slowly bumping against your shoe but if you hit it you will hurt your hand.
I know you asked what would be good for a first time playthrough but thing is if you like your character it will get strong no matter how you make it, heck even a merchant character can be strong, you could have him barter all day long, and then use his riches to buy scrolls(intentionally plural) and potions, and if I′ve learned anything about blasting enemies with scrolls & chugging down potions then it′s that it′s pretty decent.
So, what do you care about and what do you want ? Think about it, try it, and make it good
Edit: Changed the word "staff" to "scroll" to fit the morrowind section better but you get what I mean.