Agree on Potbelly, but back on topic, I'll vote for Subway because they're so much better than they were 10 or more years ago. Who remembers when Subway had only one kind of cheese (and I use that term loosely when I apply it to that White American candlewax)? When they used to cut their bread in that wedge shape that created an illusion of meat and toppings piled high? Now, a really well run Subway begins to approximate the deli sandwiches I grew up on. So, extra points to Subway for big improvement.
I'll take a Quizno's Black & Bleu salad over anything at Subway, though.