Sorry, I don't have a definite recommendation here because I don't have experience with i2s (which is a different beast). The consensus seems to indicate that silver conductors work best here. It would make sense because solid-core silver turned out to be best for my ASE/EBU digital cable.
Essentially, you should look for large awg solid-core conductors. Avoid copper only cables unless you want a warmer sound. The Nordost Heimdall would be a good cable in general. Heimdall has extremely high purity 25awg silver-plated copper conductors. Another good cable is Wireworld Silver Starlight 5.2 with 24awg silver-clad OCC copper conductors - the only HDMI cable ever made that used OCC copper! (the really old cable that still beats most other new cables). You can generally pick up a Silver Starlight 5.2 for anywhere between $150 and $350 depending. Just be patient because they are rare.
Others have had good success with the Wireworld Platinum HDMI cable (2 x 26 awg solid silver conductors). These are likely to be $600-1200 used if you can find them.
Revelation Audio Labs has a HDMI cable made only for i2s (their cable will not work as a normal HDMI cable because it's missing conductors). There are a variety of other i2s specific HDMI cables.