I haven't dove there in 10 years so have no first hand opinions at this point, or any idea how the various coral bleaching events affect diving in different areas. If you research it I'd expect to find stuff that's all over the place. (Probably why you're asking...)
I will say that you're talking about a huge area when you say GBR, and your experience is going to depend greatly on exactly where you go. There's a big difference between a week long liveaboard to more remote areas, or maybe a day trip to the Yongala if you get up that way - vs a day trip or couple night liveaboard at what they call the "outer reef", which sounds remote but isn't (relatively speaking) and is heavily dove from Cairns.
There is also diving in New Zealand, never been. Water generally colder though. Poor Knights is famous.
How long are you going for and how far out of your way are you willing to go for diving?