With all apologies to The Downtown Deli, The Hero Factory makes the best sandwiches Downtown. Owner Nicole is a laugh riot and she and her staff churn out bigger-than-your-head sandwiches at great prices (especially when you consider that their subs are really two meals). I'm a wrap guy and their club, buffalo chicken and Ceasar wraps are all top notch.
The only tip I'd give is to come early because by high noon the line is spilling out the door.