Omg that J. Crew bag is the SAME price as a Prada bag! If you're going to spend that much, go to Saks and get a brand worth that kind of money.
My personal suggestion would be Tumi. I bought one from them freshman year of college and it has held up so well. It was only about $130 on sale, but it's actually big enough to fit my 15" MBP and books, snacks, cell phone..you name it. The problem with a lot of these bags is they are so expensive but not big enough to hold anything!