Every Friday for lunch everyone at my office knows where I'm at, El Rancho. The food is fresh, the staff is friendly, and the service is fast.
I always get five or six tacos with carne asada, carnitas, and/or lengua (they also have chorizo, al pastor, tripa, barbacoa, pollo y cabeza). The generous portion of proteins are cooked to perfection, always tender and never dry. The tacos comes topped with heaps of onions and cilantro. You also get a giant grilled jalapeno, which can get really hot at times. The lime wedges you get aren't the small ones and you don't get a few of them, you get one for each taco. Tacos are $1.59-$1.75 each depending on the protein.
For appetizers, you can't go wrong with getting the chips with guac and/or queso. The chips are nice and hot. The guac has nice chunky avocados. The queso is hot and thick, if you're not careful, you'll end up pouring it on your entrees and before you know it, you ate the whole cup. They also have aqua frescas! My go-to is the jamaica. They also have tamarindo and horchata.
If you want the best bang for your buck for lunch, this is your place.