I hate cables. I don't like to think that they matter, but deep down, I grudgingly admit that sometimes they do matter. Convenience is a big factor for me. Flexibility should be appropriate to the job. Connections should be secure but easy to make and break. SQ is a can of worms.
RCA ICs = Cardas 300B that I scored decades ago. Cardas won't let the stuff out unterminated these days. Needs a hot iron. I don't know if I'm fooling myself, but they are very neutral and open, and I like them. Hacker's Mogami stuff is excellent VFM, but still inhibited relative to Cardas.
DIN ICs = Mogami, much better than stock Naim cables. I haven't put much effort into these because I want to rid my system of DIN connectors eventually.
Plugs = Neutriks or CMC locking (eBay from Taiwan). I haven't noticed any differences in plugs, although I'm curious to try the bullet plugs. Hard to imagine that it really matters, but if Martin likes them, I'll give them a go.
PCs = Pangea or PS Audio. Fatter cables on power amps do make a difference, although I haven't detected brand differences in SQ. I prefer the PS Audio even though they're more expensive because the plugs make a more secure fit, and they're reasonably flexible. Shorter cables to keep things tidy.