Which appetizer is often creamy and includes a prominent spinach flavor?

The appetizer that is often creamy and features a prominent spinach flavor is indeed the Chicago Spinach Dip. This dish typically includes a blend of cream cheese, sour cream, and a generous amount of spinach, which together create its signature rich and creamy texture. The flavor of spinach is central to this dip, making it recognizable and distinct.

Guacamole, while creamy, is primarily made from avocados and does not emphasize spinach in its flavor profile. Artichoke dip, although sometimes creamy and flavorful, focuses more on the taste of artichokes rather than spinach. Hummus, made from chickpeas, tahini, and olive oil, presents a different flavor profile entirely and does not feature spinach prominently. Thus, the Chicago Spinach Dip is the most fitting answer based on the criteria of creaminess and spinach flavor.