I’ve heard a bunch of recommendations for the same stuff over and over, yet when it came to where I dropped my hard earned $ for interconnects it was Hapa Audio that blew everything else away. Known more over on AudioCircle, Jason is a one (possibly two) man show and does phenomenal cables. They are not real cheap, but comparatively speaking I have been able to put off big time gear upgrades because the cables boosted performance beyond what I ever thought could be done. At that point, his cables are an absolute bargain.
For speaker cables, if you’re handy with a soldering iron then have at a DIY set for pennies on the dollar. I made a set that took me most of a day to build, and were a big improvement over the Audioquest I was using. I finished mine in KLE banana plugs, but most importantly just don’t use gold or anything plated over brass. Yuck.
Another option for DIY or if you feel like just paying someone else to make you a top notch set of speaker cables, look at the GR Research. It’ll run you a few hundred $, but again a bargain compared to a similar performing option from another big name operation.