Hi @Graham1-00
Best?, it is impossible to say without knowing what you are connecting.
Looking at your manual and specifications you can use all 4 ports for normal viewing. The only “special” HDMI ports are 3 and 4. HDMI 3 (ARC) should be used for connecting an AV Amp or Soundbar if you have one. HDMI 3 & 4 have VRR Variable Refresh Rate and ALLM Auto Low Latency Mode. If you don’t know what VRR or ALLM are then you can safely ignore them. So if you don’t have any special requirements you can use all 4.
https://www.sony.co.uk/electronics/support/televisions-projectors-oled-tvs-android-/xr-55a84j/specif...
HDMI IN 1/2/3/4 (HDCP 2.3-compatible) Video:
4096 × 2160p (50, 60 Hz)*1*2, 4096 × 2160p (24 Hz)*1, 3840 × 2160p (50, 60 Hz)*2, 3840 × 2160p (24, 25, 30 Hz), 1080p (30, 50, 60, 100, 120 Hz), 1080/24p, 1080i (50, 60 Hz), 720p (30, 50, 60 Hz), 720/24p, 576p, 480p, PC Formats*3
3840 × 2160p (100, 120 Hz)*2*4 Audio:
In eARC (Enhanced Audio Return Channel) mode
Refer to the online Help Guide for details. Except eARC mode
5.1 channel linear PCM: 32/44.1/48/88.2/ 96/176.4/192 kHz 16/20/24 bits, Dolby Audio, Dolby Atmos, DTS
eARC/ARC (Enhanced Audio Return Channel/ Audio Return Channel) (HDMI IN 3 only)*5
In eARC mode
Refer to the online Help Guide for details.
In ARC mode
Two channel linear PCM: 48 kHz 16 bits, Dolby Audio, Dolby Atmos, DTS
*1 When 4096 × 2160p is input and [Wide mode] is set to [Normal], the resolution is displayed as 3840 × 2160p. To display 4096 × 2160p, set [Wide mode] setting to [Full 1] or [Full 2].
*2 Refertotheonscreenmenutoset[HDMIsignal format].
*3 RefertotheonlineHelpGuidefordetails.
*4 HDMI IN 3 & 4 only. Use the Ultra High Speed HDMI
Cable to connect.
*5 Connect your audio system to the HDMI IN 3 to route
TV audio to your audio system.
