It's my assertion that everything is viable in this game. Fighter is pretty fun in my opinion as is the rogue. They can work well together with the fighter supporting the rogue and playing the meatshield. You also have the ability to get followers in this game that will fill other roles such as mage, ranger, cleric, so on. You can either get them from talking to people in the first city or getting henchmen once you unlock the Hall of Heroes.
Ultimately, you'll really end up with 4 people in your party so you can really build out the group as you want. I have yet to do a full physical/no magic playthrough but it could be fun. Ultimately if you do get magicians, you'll occasionally have an issue with placings fields and spells in such a way that it doesn't harm your melee characters, but it's still viable.
I would say for you, that if you enjoy the melee playstyle, give some of the others a shot with henchmen/followers. I am usually a rogue player, but I found that I love the magic system in the game =)
