Default should not be SSIM or PSNR tuning, it should be the "untuned" setting

[erazortt]

Following the x265 manual on the tune parameter (https://x265.readthedocs.io/en/stable/presets.html#tuning) it seems that SSIM and PSNR should not be the default setting for this plugin:

The psnr and ssim tune options disable all optimizations that sacrafice metric scores for perceived visual quality (also known as psycho-visual optimizations). By default x265 always tunes for highest perceived visual quality but if one intends to measure an encode using PSNR or SSIM for the purpose of benchmarking

Also the "untuned" x265 misses from the dropdown, following the bold emphasised part from the quote this should be optimal for actual images.