TBB is quite the echo chamber sadly, you still see posts saying they wont go with Zen because they had a single-threaded performance issue years ago.
Although I will admit I have a bias against Origin Broadband because their network underperformed and they went through so many infrastructure changes that never seemed to improve it much. But then again, if they were dirt-cheap for a backup, I wouldn't completely discount them.
When you look at the positive Zen posts I think it says a lot that they are willing to move people from TTB backhaul to Openreach, if you have a performance issue in your area, despite it costing them more money.