I'm a begginner, and I havent exactly decided on what my character should specialize in. In your opinion, what would be the best class to go with?

That's the beauty of the game, there are no classes. Just play the game and try everything, your character will get better at the things you use the most.

the best way is to just start and play what you want. find out what works for you and what you enjoy.

There arent any classes per say, just what you do/use levels up with you. You can though still play as a Thief, Warrior or Mage, by restricting what you do if you like, but you dont have to put perk points into skills your not interested in, yet still use that skill.

What do you like doing ?

Fighting toe to toe with enemies = Warrior

Hidng in the shadows & sneak killing = Thief/Assasin

Summoning Creatures to fight for you & use spells = Mage

Or you can mix them all up as you like.

Fight toe to toe + Magic = Battlemage

etc...