What cable companies make the best cables and sell them directly?

Not many, I suspect. Why would you think otherwise?

because I see endless debate on things like cables and very little if any discussion about optimizing a room (which includes speaker placement)

granted, I don't spend much time here anymore so maybe I'm wrong about that, but historically my view is accurate

I have used Blue Jeans Cables several times.  They are very well made and nicely terminated to your specs.  Also reasonably priced.

I also agree with Herman's commments...moving your speakers even a few inches makes much more difference than cables.

Chin Audio Labs.

Sometimes a direct seller is less likely to discount so as to avoid being accused of undercutting their secondary retailers. Sometimes returns are only accepted for replacements and not refunds. When dealing with a direct seller those replacment options can be much more limited than can sometimes be the case with a secondary reseller that might carry additional lines.