[dleviwing]

Nobody;
If you use the concept that mass is a function of uniform motion, then the solution is very simple. The simple view is that if you increase the uniform motion (linear, angular or wave symmetry motion) of an electron, you can increase its mass to that of a quark. The quarks actually are an increase in both angular and wave symmetry motion. The positive quarks are quantitatively higher frequency wave symmetry and the negative quarks are basically a quantitative increase in angular motion. This is denoted by charge. The actual physical quantity of substance of a quark and an electron may be as you suspect; no difference. The greatest difference is in how they interact with the substance of their environment (space or Aether).
This is only my interpretation using my Toronic concept of matter but it does work in all phenomena form the micro to the macro. The speed of light is not a “Speed Limit” to the motion of fundamental matter.