The whole A9 vs A7 III debate will always rage on, the A9 is better but for so many different reasons apart from its AF performance.... anybody who thought the A7 III had the identical AF performance like the A9 for £1999 was a little optimistic.
- EVF
- 20 fps
- Deep buffer
- 100% silent shutter (no distortion)
- Drive Mode Dial
- Blackout free EVF
- FTP / RJ45
- 6K -> 4K Recording
- CMOS RS with high response rate
You could argue that for the additional £1800-2000 premium, the Sony A9 isn’t worth it over the A7 III.
It comes down to your requirements, others just want the best of the best regardless of the outlay