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

My experience. I can afford about $50 on RCA cables.

Audioqest Evergreen had a bad connection after the first removal. The Worlds best cable had no issues.

Speaker cable =install gear 10ga oxygen free copper. My friends joke and call me "ears" I notice nuances in music, love music, accuracy in instrumental reproduction. a Sax, bass, trumpet cymbal, voices, sound right. These are cheapo alternatives for people like me that have little cash, but like quality and excellent sound. This works for me. It is always fun to hear other people’s experiences.

I will add one more thing to the conversation. Your age and your hearing may impact how much difference cables make. I don't disbelieve people that say they notice major differences between cables however at my age and with my hearing rolling off around 12,000 Hertz those things they notice may not be apparent to me. So besides all the other decision factors that have been mentioned I would suggest taking that into consideration.

I went with a loom of AudioSensibility cables and would highly recommend them. 

You can choose between OCC copper or silver. I went with silver for maximum clarity and am stunned by the result. 

I vote for Zavfino and Grover Huffman cables.  Both make a full spread of power, interconnect and speaker cables.  I have Cullen Cables as well and those cables were very solid.  I did though hear that Patrick Cullen is no longer an independent operation.

I think VH Audio? is another standup, high-value option to check out.  So many options at this point it’s a bit mind boggling.  Read reviews to thin down the herd and then buy used and/or go with a direct seller with a good trial policy.  To me, both these strategies are almost identical price wise if you negotiate good used prices.