I found Zone Alarm to be lacking, with updates this year making it work worse for me.
I had purchased AVG Paid anti-virus last year and found out my paid update this year included a firewall.
ZA went into panic mode, with popups, as I uninstalled it. Ethernet disconnected.
I ran the AVG paid instlal agina, and selected install firewall this time.
I did find that you have to tell it to ask for a program's permisison to go outside my computer. It doesn't do that automatically.
What do you use ? And how well does it work for you ?
Not going to change mine. I'm just curious.