Check out Byby's for good Oaxacan style Mexican and other standards(tlacoyos, huarches, huitlacoche quesadillas). It's a small place with the ambience of eating in someones house, but the food always delivers.
For a little bit nicer ambience and good hand made tortillas (only with certain dishes, be sure to ask) you could try El Tesoro. They serve good steak tacos and a decent bowl of red posole.
Both of these places have been documented here previously. Do a quick search.
BYBY'S.
142 W WASHINGTON ST.
West Chicago, IL
630-562-1710
El Tesoro
129 W. Roosevelt Rd.
West Chicago
630-293-0129