Standard mage is pretty easy and straightforward: pick up the dark necromancy college for harm and conjure spirit. Harm is the bread & butter damage spell, while conjure spirit gives you some additional content by talking to the dead. After that, the force college for shield and eventually disintegrate. And finally what I can the "convenience" college for disarm, unlock and the amazing teleport. The most important factor is keeping up high magickal aptitude, which means you have to forego tech. Main stat is willpower, while intelligence lets you keep up spell such as haste or tempus fugit running.
That said, I liked my non-offensive mage better. She focused on the mental and temporal colleges to disable her enemies (and later also on morph, turning them into sheep instead
) and had high charisma for plenty of followers, who did the actual fighting. Not the easiest character to start with, though.
My absolutely favourite character was a techie, but you need to enjoy crafting for this, as he spent a LOT of time going through junk to find components for his inventions. Started with explosives (and some throwing skill) for stun grenades, which are very helpful when you're a squishy scientist. Ended up focusing on mechanical engineering to build himself an army of robots. Same as with mage, the most important factor is to get your technological aptitude high, while intelligence is required for learning technology disciplines.
Tbh, I don't recall the detailed builds of each character anymore, but Arcanum is not a game where you have to min-max your character to succeed. Generally, if you have never played it before, then the one thing I would not recommend is a low intelligence character, because while the dialogues are funny, some important npcs will flat out refuse to deal with an idiot and you'll miss out on some content. It's great for a second playthrough, though.