I can't give you any first-hand opinions. As a matter of fact.. I can't give you any (personal) opinions!
What I can provide you with is a long thread, which was posted here, titled "Comodo or Zone Alarm". Out of the 39 posts, you should find varying opinions. Please keep in mind, the thread is almost 3 years old.
Another option might be to read through the test results at Matousec.com.
Best of luck..
Look at just the firewall aspect of the program.