a1 leather with several handles is my choice. hardwearing, simple, easy to clean. aluminium sounds a bit odd. dents, damage, weight, price, lots of issues. you could always make one out of butter paper with spit as glue
a3 in work, for planners meetings, for intelligent clients etc.
most college work however would be a1 for presentation purposes. reduction of college work is expensive and time consuming. i've ended up with health mix of the two. depends on the prospectives employers fancy as to what he'll devote his attention to
I have roll upon roll of A1 presentation sheets lost in a cupboard somewhere, i find that i generally have no use for them once my crits etc are over. A3 is simple & convenient for showing work to others. Presentation isn't always essential though - i have a friend who got a job after an interview at quite a prestigious firm with 4 random A3 sheets!