Have to chime in on this one..
Z Avenger is my primary driver, my workhorse if you will. I threw champ Teebirds for many many years but switched to the Avenger because:
1. I like the way it feels in my hand. The bottom rim is sharp. I can grip it hard.
2. Love the way it flies. Very consistent, but it does depend on plastic and wear like any other disc.
3. Surprising distance. I throw a Nuke as my longer range driver but it doesn't really go that much farther then my Avenger.
In general, a brand new Z Avenger is overstable. It takes a while for it to wear in.
The first run Z to me seem less stable when brand new.
My favorite run is very rare (and I'm always looking to pay cash for these). They are marked Z Avengers but the plastic looks and feels like X (opaque). Usually they are orange and they were created around 2006-2007. If you can get some of these they are so sweet. Good grip, flat, fast and very glidey with a long straight flight and predictable fade.
I also have a quadruple stamped clear Z Avenger that is flat like a pancake. Right now that is my favorite one in my bag but it also is not as stable as your typical new Z Avenger. I like them a little worn in so that with a slight hyzer release it will straighten out and carry for a long time.
Thanks for letting me rant about one of my favorite discs ever made.