There are a million bags out there in that shape and size. Nylon, cloth, leather, pleather, etc.
But I believe there is only one that will look as good as a tumi. A tumi bag will easily outlast several (many?) of the less expensive bags and be worth the investment. Seriously, nobody is harder on a laptop bag then I am, and my outlet tumi bag really holds up to the abuse.
I say get the tumi.