Quality varies a lot among different brands of pencils, and quality can also be an subjective thing depending on what sort of technique you employ when you use colored pencils, and personal preferences regarding how you want the color to look. There are pencils that blend and layer so well that it's not necessary to HAVE "24 skin tones" (whatever the hell that means). You should be blending several colors together to achieve a wide variety of realistic skin tones for portraits, (including whatever colors you choose for things like shading and highlighting. I would recommend you do some research. Read online reviews on each brand of pencil you are considering buying. There are also numerous artist reviews on YouTube where different people give their opinions concerning different colored pencils, and where you can see these pencils demonstrated.
Your "best answer" mentioned paper. Paper is actually very important. Pencils (as well as other artist media) react differently on different kinds of paper. Using a high grade colored pencils on cheap thin printer paper will not give you the same results as using a thicker, more "toothy" drawing paper made specifically for colored pencils and other dry media where you may want to do a lot of layering and blending, and where you can do repeated erasures without too much damage to the surface (to correct mistakes, or "lift" color for highlights or other effects)