Two unmentioned in the poll that have had stronger offerings than others I've sampled:
Carnitas Don Rafa / Sabas Vega: carnitas dinner, $8. Big sturdy partitioned container of thin but savory beans, rice and corn, and a large portion of carnitas (with spicy pickled nopalitos), which stand up very well to truck conditions. The carnitas definitely have some lean tenderloin in with the shoulder, steakier and not particularly crisp, but still moist and good. Cold red and green salsas on the side. Seen at both UChicago and UIC recently.
Bergsteins NY Deli: Pastrami on Rye, $8. Bountiful sandwich of well seasoned pastrami with fat that had seeped into and crisped the bread in the hot truck conditions but did not saturate it. Meat was a little chewy from over-steaming but still tasted really good. Pickle and Gulden's included, also picked up a wax paper bag of kettle chips for a buck. Other common truck offerings are the signature sandwiches, potato pancakes, black & white cookies, and matzoh ball soup, but Bergsteins reinforces (to every customer) that they'll put anything from the regular menu on the truck with your name on it if you order in advance. At 58th and Ellis every Thursday lunchtime. I'm pleasantly surprised to find great reports (none really recent) on the bricks and mortar
shop I had overlooked entirely.