Quality comparison between Qwen 3.6 27B quantizations (BF16, Q8_0, Q6_K, Q5_K_XL, Q4_K_XL, IQ4_XS, IQ3_XXS,...)

The following is a non-comprehensive test I came up with to test the quality difference (a.k.a degradation) between different quantizations of Qwen 3.6 27B. I want to figure out what's the best quant to run on my 16 GB VRAM setup. WHAT WE ARE TESTING First, the prompt: Given this PGN string of a che