I'd probably go with a mage, as on the battlefield I'm more of a tactics person and I find the concept of uncovering ancient mythical magics as I plunge deep into the catacombs of the world to be very pleasing.
That and in my daily life I dabble with chaos magic, which while not as flashy can do some very interesting things and shows that I have the mental aptitude for such a thing.
Now if I were forced into a class based on who I am I imagine it would be a spell sword, as the game world isn't likely to ignore the fact that I'm 6'5" and can get aggro, and the spell part relates again to my general search for wisdom and ancient power.
Also, why don't more RPGs start this way? At least then I wouldn't be bothered when people are explaining the world to me. There could even be a moment at the end where I choose to stay in the fantasy world or leave (and if I stay endless questing).
Also, if I were to write such a thing I'd have your character realize he's in a video game if he goes the mage route (as what bigger and more obvious secret is there to learn when you manipulate the nature of reality with a glance).