I'm a die hard fan of Thi Thi but I also enjoy the subs at Trung Nguyen. Both places offer similar pricing and subs, but they taste different. I like the sauciness of the assorted sub, how pickled the carrots are, and the lightness of the baguette at Thi Thi. At Trung Nguyen I like the proportion of veggies, meat to bread ratio, the flavour of the sate chicken sub, and the shorter line-up.
I picked up some subs for a Sunday afternoon feast and I was impressed with service from the female owner at Trung Nguyen. She told me to call her the next time and she would bring it outside so I wouldn't get a parking ticket. What a sweetie! Now that's service.