The "best type" is subjective, but it really comes down to preference after a certian level of quality. I recommend MDPC-X, but lots of people just love paracord, especially the stuff Lutr0 makes.
If you're doing full custom wires, you will need a crimper, wire stripper, lighter, soldering iron, and Xacto knife (or any other sharp blade). You really only "need" a lighter and blade, though, if you're not doing custom wire lengths.
You will want, or perhaps need new connectors, also known as terminals; i.e, the plastic pieces that plug in. You want to use the ones that came with your PSU if you have a non-standard one, like a lot of Seasonic PSUs, which break the 24 pin cable into two individual connectors at the PSU-end, but if you have red, clear, baige, or any other connector color and you don't like it, you can buy new ones in most any color te meet your preference. I'd just use black :|
Lutr0 has some fantastic tutorials on the subject, as well as the OCN community. CLICK ME.
Extra advice? Don't use heatshrink. It looks ugly unless you use reall short lengths, do it incredibly well, and spend way too much time over it. Heatshrinkless is just as physically strong of a connection, looks better, saves you money, and is easier to do (just as hard to do well, but easier to get it looking good, if you understand). Just melt the paracord, or sleeve, over the bottom(ish) of the crimp.
