I went to 3 places all near each other. I only got sandwiches from 2, Yummy Express, and P&N Sandwiches. The third, Lucky Sandwiches, did not look very eager to serve me - at dinner time, they said they were out of bbq, and they had none of the other dishes out in front as the others did. I said thanks, and left.
These three places, and a 4th, for which I found a sign but could not find the entrance to - Le Petit Cafe - are all off Middlesex or Branch, where they split after the Thorndike/Rt 3A interchange. This is near the boys club.
The two I did buy sandwiches and spring rolls from are on Branch right across the street from each other. The Angor Wat grocery store is right next to Yummy Express, and across the street from P&N Sandwiches.
Both places have excellent french bread rolls - I wish I knew their source - nice and crusty, and a large, uneven holed, tasty crumb. The Lowell area has a dearth of good bread. Both had fresh shrimp spring rolls in packs of 3, and the small fried rolls individually, in front of their glass deli cases. Yummy Express had some other prepared items in front. Both places offered cooked dishes as well.
The spring rolls were the same in both - as good as most restaurants - a couple of sliced shrimp and a good amount of basil in each. The sauces were very good.
The sandwiches all had about the same amount of the marinated carrot and daikon strings - both had good fish sauce based flavor.
The difference: the meat filling at P&N was not only more plentiful, but better tasting. They had a paste - not exactly a pate, but a flavorful paste they spread down the bottom, and the meats, mostly pressed meats, were plentiful and delicious. Yummy added cilantro, but P&N's didn't need any. The combination sandwich at P&N has a variety of pressed meats plus some chinese style bbq pork - this is definitely my favorite.
P&N's is also cheaper, but not by enough to matter. Theirs was $2.00, while Yummy's was $2.25.
The 3-pack of fresh shrimp spring rolls were $1.50. Pretty cheap meal - a 3-pack of rolls and a sandwich for $3.50. Now that's what I call good, fast food!