There are many variables to consider when selecting a briefcase. But the rule of thumb is that all aspects of your wardrobe should communicate the same message and this includes accessories. A fabric case is more causal than a leather (dressier) briefcase. And when worn with a suit and tie, this combination creates a disconnect; therefore you are communicating two different messages. Carrying a fabric case when wearing a more casual makes a better connection.
It also depends on the type of work you are in. If you are in a creative industry, you can get away with a more fashion forward bag. For you, the briefcase is leather in a cognac color and the style is not formal or conservative. It goes great with jeans and suits. It also goes with your warm coloring so it will harmonize with your belts and shoes.
I would definitely not carry the old fashioned leather case that is rectangular in shape with flip locks. This will definitely put you in the old man’s category!