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

"Best"?  There is no answer to this question.  Your equipment & room combination is unique as are your tastes so the answer is rather personal. Your question implies you don't want to go on a long hunt though.  But it's personal so you have to.  

Really, beyond properly assembling a cable from quality components, and matching electrically, the differences are mostly tonal.  They're all "the best", just different.  There are known generalizations about copper, silver, etc. to consider.  Call your component makers and ask for suggestions at different price points?  Call their dealers and ask the same question. Might get you a good starting list.

In the meantime buy a set of Blue Jeans.  As others have said they use industry recognized quality components and do a great job of assembly at a reasonable price.  No functional reason to spend more or change them out.  Use them as a quality starting point. 

To shorten the hunt call The Cable Company or someone like them that has a broad selection of both new and used. Tell them your component list asking for a system opinion at various price points. Ask what they think of the models on your list. Buy a new or used set or portion of one and then return/exchange with them until you find what you like "best" or they stop you.  You'll either find what pleases you more than the Blue Jeans or you'll sell the last set on the used market and stick with the Blue Jeans. 

There is NO BEST CABLE. It is FALSE that the more you spend on a cable the better is gets. That said, there are many excellent cable makers out there. You could try Morrow Audio, they have a number of lines at different price points. They are well made and fairly priced (at least most of them are). You should expect to pay somewhere in the neighborhood of a couple of hundred bucks on up for say a one meter pair of RCA connecter cables. 

People will pay thousands for a cable. IMO that's cool if you have the money and want a particular make like Nordost or whatever at the higher end-- but make no mistake, you will hear differences, but no one can rank a group of quality cables by price. Your unique combination of gear is a big factor in which ones will sound the best to you. 

A lot of people in this hobby treat cables like bling-- which is cool. Me personally, I go for quality build and materials, and then how it sounds, and prefer not to spend the stupid money on cables-- and use it elsewhere-- like phono cartridges, more vinyl, etc.

Check audio sensibility web page if you are truly looking for cables.

I went direct with Grover Huffman cables - Pharaoh speaker cables and ICs. Power cords next.