There are hundreds of briefcase styles and makers. If your friend is picky at all he should specify more clearly what he prefers. You want to buy him a durable briefcase, you don't want the case to annoy him for decades.

If you want large size and light weight, it generally means either nylon or other cloth, or hardshell. Personally I dislike nylon.

If he really likes Tumi but it is too small, perhaps buy him a bigger one.

Personally these are more desirable to me:
Glaser Designs
Filson
Swaine Adeney/Papworth
Daines and Hathaway
Mulholland
Schelsinger
Korchmar

On the very expensive end, Valextra

I think Saddleback is hideous and too heavy but your mileage may vary