For what we do, as long as it will adequately conduct the electrical signal, it's fine. I've tried a lot of different things. If I'm working with complex wiring schemes or small terminals (like the ones on push-pull pots), I'll use a very small wire, like a 28 or 30 gauge. Otherwise, something like a 22 is fine. Solid core wire is a temptation, as it's easy to work with, but it's more likely to fail over time, so stranded is the way to go. The insulation material comes down to personal choice. Cloth push-back is fun, but bulky. So mostly I prefer simple plastic insulation. Multiple colors help you keep track of what goes where.
Then you get into insulated wire. I'm not a big fan of the braided wire, because it likes to poke me and make me bleed. I prefer the kind that's insulated in foil. I've even made my own from foil and heat shrink plastic before, in a pinch.
That silver tinned stuff sounds really good though. I want to try some of that stuff.