In Chicago, if you are served a tamal-like (the singular is tamal, not tamale) item in a banana leaf, it is probably Oaxacan, Guatemalan, or Peruvian -- or it is a Puerto Rican pastel.
The smooth "masa" in Central Am. tamales is attributable to the use of rice flour as well as corn.
Zim has discussed a place to get good tamales Gutemaltecas. I get mine from my aunt.
Good hallacas Venezolanos can be found at Caracas on Clark at Devon.
Your best bet is, no surprise, La Unica. Particularly around the holidays, La Unica has a very wide variety of both locally-hand-made and commercial (Goya, eg) tamal-like items in the freezer representing various South and Central American countries. The tamal is a Christmas item of particular importance, with families having tamal-making gatherings not unlike the Polish pierogi-making party.
Among tamales, the use of a corn husk is actually less common (if one goes by the numer of styles) than the use of a banana leaf. Corn husks are commonly used for the well-known Mexican tamal as well as the Cuban version.