Two completely different styles of briefcase there. The Mulholland is a single gusset, similar to a mailbag or angler's bag, while the M&W is triple gusseted. A bag with gussets is much easier to manage than a large bag with one compartment, as stuff has less a tendency to slide toward the bottom. If you carry a laptop, the M&W will be the better bet. The M&W appears to be made of Horween leather, which is some of the best leather available. Not clear what leather Mulholland uses. The lining is what kills the Mulholland--Nylon.
I'd want to know more about the quick release on the M&W and the Mulholland. EDIT: M&W outlines how their quick release works on the website. Pretty nifty, actually.
Mulholland craftsmanship is pretty good, but . . . the M&W appears the better deal.
I have the Mulholland in lariat. I got it discounted on Sierra Trading Post (check there to see what bags are on offer.) There's nothing wrong with it at all, decent construction and leather, but I struggle to think of it as a "briefcase" ... a bit too casual IMHO. (No comment on the other bag linked ... don't have one.)