I've never thrown a glow Z Buzzz, but I'd agree with everyone else and say Z. I use my FLX for turnover shots, my Z Buzzz replaced the Wasp in my bag. Great disc in the wind, now I just need to figure out who walked off with it.
I have to say the Glow Buzzz is the most overstable. But I do have a super flat top buzzz in regular Z plastic thats stable. I don't think it really makes any difference they will all hold a hyzer line very well.
Threw my DX from extrem elevation on Easter sunday out at my buddies ranch. I'd say maybe 300' of elevation, I'll check it with an altimetor next time I'm out there. It was a beautiful sight, let it out on hyzer, it flipped up and ran, just as it would die left it would pick up speed again and turn. Would say the shot ended on a patio at the bottom of the property about 900' away. No way I'm gonna subject my Z Buzz to that, but thought it interesting to see the mechanics of disc flight in action like that.