I am looking for a high-quality HDMI cable for I2S from a CD Transport to the DAC...

The AudioQuest Vodka is pretty awful: bright, thin and “tinny” sound.

Audioquest Vodka HDMI cable uses really tiny 30awg conductors.  This is why sound is so tinny and bright.

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.

I could not advise you on that since I have never used i2s myself.  From what people say, i2s is superior over S/PDIF.  However, some things to think about:

i2s - this requires a very short cable (1-2 feet).  The interface does not work well with longer cables.  Also, the largest awg conductors you will see are about 24awg in the largest HDMI cables.

AES/EBU - you can run this very long (15-20 feet is no problem).  It also opens you up to a larger selection of cables and also cables that have much larger conductors (like 18 or 19 awg).  In my experience, this gives you the best bass and depth of sound.

Uhm, if you use the HDMI cable for actual HDMI audio/video source, then 2 meter is definitely better.

However, if you are using this for i2s, then you still want the cable as short as possible (like 0.5 meter).  The i2s interface is different and was not designed for long cable runs.  I'm not sure how well the Heimdall will work out for you.  Hopefully, it will be an improvement.

For AUS/EBU cable, Tara cables look good, but they definitely get expensive.  I would ask them what size conductor they run.

I just recently had a discussion with another forum member.  He ended up getting an Acoustic Zen Absolute 110 cable.  This uses a large 19awg solid-core pure silver conductor.  It's close to my own custom built cable.  It is one I would recommend at this point.