I'm a huge fan on Backup Exec. I've sold and admin'd both. Much prefer BE. ArcServe tech support is terrible. You call, they call you back, hours or a day later. Just not acceptable to me.
You do pay for BE support. But anytime I've needed them, they've got me going again, quickly. Which was important for me while I was consulting and being paid by the hour. I couldn't wait at the site, and being called back on CA's time table, sure didn't work for me.
I'm sure you'll find both sides well represented here. I can only go my experience and those of others I know, who have used both, and stuck with BE.
Good luck!