Out of the three, ZoneAlarm is probably the easiest to use while Outpost and Kerio offer slightly better protection. This is a very general statement of course. Much depends on how much effort you want to put into learning how best to use the firewall you choose, but any of the three will more than suffice.
If you are on a home computer you will have more chance of winning the lotto than being hacked. Choose any of the above, personally I would prefer Outpost as it is non-intrusive but then again, I don't use a firewall ;-)))