Cardas Litz for critical signal applications when the construction and cost permit it.
Belden 1701LC for small signals and where the Litz wiring is very difficult (small PC eyelets for instance).
The Belden is cheap, each foot contains four twisted pairs of #24 AWG Teflon insulated solid copper wire with no silver plating. I do not like the edgy and thin sound of silver plated copper conductors typically found when using Teflon insulated conductors (solid silver is fine). Buy at least 10' and it's only $1.45/foot of cable or ~18 cents per foot of conductor. Sounds pretty smooth also.
For filaments, etc., 18 gauge Teflon insulated silver clad copper stranded. The insulation holds up to heat so very well.
For ground buses, the largest single strand copper in my box at the time. Usually #6 AWG in the big boy amps.
If cost and labor time were not issues, I'd use the various sizes of Cardas Litz wiring for everything.
https://www.hndme.com/productcart/pc/vi ... tegory=210Cardas TTFMF!