Before answering this question, both TVs are OLED TVs, and they are both excellent. Before discussing, let's take a look at the parameter comparison of the two TVs:
LG C9P:
AI audio/picture chip α9 Gen2 chip
120Hz screen
1.07 billion colors,
2+8G running and storage space
The peak brightness of the screen reaches around 850 nits
HDMI2.1 interface (support VRR)
Support Dolby Vision + Dolby Atmos
97% DCI-P3 color gamut
The Web OS system is used. Although it supports the installation of third-party software, it is not as good as Android.
SONY A9G:
Adopt MT5893 A731 quad-core CPU
Sony X1 image quality chip flagship
120Hz screen
3+16G running and storage space
4K Xunrui image quality engine
Brightness around 500 nits (peak at around 800)
94.5% DCI-P3 color gamut
Fourth generation screen sound technology
Support Dolby Vision + Dolby Atmos
No HDMI2.1 interface
From the above comparison, both TVs are very good. But in terms of screen peak brightness, interface, etc., I recommend choosing LG 65C9P.