I don't believe there are any ESP8266 modules with FCC modular certification yet.

I prototyped a CC3200 module but stopped working on it when it became apparent that the ESP8266 was here to stay. It's a simpler chip with fewer available GPIO pins and less processing power, but it can be packed into a much smaller area than the CC3200 (CC3200s require 3 separate power inductors!).

It's important to note that the ESP8266 may well be more open than the CC3200! Much of the CC3200's functionality is packed into a binary blob from TI, and the chip runs this code on a second core that you don't have any control over.