Alot of people use Comodos firewall due to the publicity it has been given. However it didnt do so well in the tests.
Top 3 rated:
Online Armor Personal Firewall 3.0.0.190 93% / 84 10+ Excellent
Comodo Internet Security 3.5.55810.432 FREE 90% / 84 10+ Very good
Online Armor Personal Firewall 2.1.0.131 FREE 89% / 73 10 Very good
Not sure why Online Armor v3.0 FREE wasn't tested (results were updated a week ago), however, it seems to be holding up pretty good. If you scroll down to the bottom of the page, you'll see that Online armor has scored pretty high in the past, so i don't think it'll do too much worse even though it wasn't tested.
And for those that are interested about Comodo Firewall:
Comodo Firewall Pro 2.4.18.184 FREE 55% / 73 7 Poor
Please, don't start up a debate about which firewall's better then which, because in the end, it all comes down to personal preference. I choose Online Armor FREE based on these reviews (before the test results were updated, online armor free was rated 2nd to comodo), however, for all i know, ZAP or KIS may perform better.
Results and comments - matousec.com