First pair black and first pair brown as first pair are sleeker and more formal and the second more rugged and casual. However the second in black would give you more of a biker look. They are biker lite though. I do have the second pair in black myself, but chose that colour as I could just about get away with wearing them to work and I didn't think I would with the brown.
Interesting that Clarks are getting better with their Acne Pistol wannabes.