While there may seem to be many firewall systems on Linux, in reality, there aren't; those different firewall systems are different front-ends to iptables So you have a big choice of front ends, but they are iptables underneath.
So, to get an answer that you would consider useful, you'll probably have to actually ask the question in a clearer form: What do you want to do or what is it about iptables as you currently see it that you are tying to avoid?
Note that the reply from win32sux was a correct one to the question that you had asked; here's another one (which I believe will also not help you, but it is an answer to the question that you asked); Ipchains.
Now I am fairly sure that this answer won't help because, in principle, iptables is an older, less sophisticated version along similar lines to Iptables (and you'll need an older kernel to even be able to use it) and so I can't imagine any situation, except maybe embedded, where Ipchains would be an advantage. Except if you are determined to use an older kernel and can't cope with the complexity of Iptables, but slightly less complexity would make it good for you. That seems unlikely, but I am only guessing what you might want.