I haven’t got a load of experience with lots of trainers, but I’m happy enough with my kickr v5 with regards to ERG response - I don’t feel as though I have to give intervals too much thought.
There was an interesting post somewhere on here by @gpl saying that he felt response was slightly quicker with BLE rather than ant+. I’m an ant+ user but i’m going to start using BLE and see if I notice a difference.
EDIT: found it Bluetooth vs ANT+