Arcserve has the pretty gui if that is what you want, but Networker will give you much better performance and reliability.
In medium/large environments Networker wins hands down. Don't even consider Arcserve.
A real world example. I have a customer who used Arcserve to backup 50 nt servers, he needed 5 Arcserve servers to get it done in the backup window. They chose arcserve because of the pretty gui. 6 months later they tested networker again, and found that 1 networker server did the job. And it took less of the SA's time, He went from 4-6 hours per day to manage backups/restores to 4-6 hours per week.
networker is not the easiest product to learn, but when you do it just runs and typically it runs very well.