I used Comodo for a year and thought it was a high maintenance item. All the flexibility often led to being told "you were in the wrong mode" when things happened. And strange things did happen, along with sporadic logging that made some things unexplainable as well as unpredictable. It is what motivated me to learn WireShark.
I never put it on my other computers because of that, but as a beta tester and moderator tried to keep up with the problems. When Comodo decided to become a suite, the evolution of the Firewall and HIPS were second priority, and even the Bugzilla maintenance attempts were abandoned. But tests show it works very well if you are willing to have faith.
I have been using OA for 2+ years and find it at least as effective with less mystery. But maybe Comodo softened me up-although actually I was using Kerio 2.1.5 before that.
I am trying out Private Firewall on one Vista computer, and think it looks very effective and promising. I just wish they had a forum.
Haven't tried the latest ZA but always liked it when I used it before as a Firewall for the masses.
And never used Outpost, but a lot of the people here like it. It has just never bubbled to the top for me.
So my current choices on the machines I actually own are OA on 3 machines (W7, Vista, XP) , Windows 7 firewall on 1 (so my wife never sees popups but is still pretty well protected), and Private firewall on a Vista backup machine just to try it out. And of course they all have some version of Avast! 6 besides, along with a couple with Prevx. So I don't know how to define "better" either, but the machines are used for different things and reflect firewalls that I am comfortable with for the applications. I have used lots (dozen+, not hundreds) of firewalls, though, and don't know your experience level and how much you want to interact.