I totally understand this inquiry with regards to the combination of stiffness and gauge. To me, it is entirely related to the shape and size of the neck, and how the neck responds to relief on the particular bass in question. I can contrast two basses of mine for example: 1) Fender CS '59 Precision. This thing has a massive neck with tall frets and took me a long time to find the right combination of neck relief/string gauge/string stiffness. Turns out DR Pure Blues 45-105 and .010" relief work the best. Round core, aka slightly more flexible, and the size of the string feel suited to the neck. My fretting fingers don't have to work so hard due to the round core, and I can dig in when appropriate. 2) Sadowsky UV70 Jazz. The neck is truly a feat of engineering. I keep the relief at .006" and use DR Nickel Lo Riders 40-100 on it. The insanely low action with the stiffer string helps enable fluid motion without having to worry about unwanted clank. The lower gauge is easy on the fretting hand but not floppy under the plucking hand. I would love it if I could just find one gauge and brand set to work on all my basses, but they each have a specific purpose and getting the stiffness/gauge combination correct is, to me, the key to unlocking the potential of every instrument.