The first one is no longer being sold.
The second and current one is exactly the same as the ESP-12 except it has a ceramic SMD antenna AND an external antenna connector in place of the PCB one.
The ESP-12 has FCC certification (for real, AI-THINKER had it tested) but the ESP-07 currently does not. The external antenna connector is going to make FCC cert difficult.
ESP-07 and ESP-12 are likely to be the more popular ones, unless you want something more breadboard/jumperwire friendly (ie 0.1" header instead of 2mm).