Banana heads - Eldar Yellow

As readers of this blog will no doubt recall, I have been working on Imperial Guard and Tau for an eventual skirmish game.  Not content to have two unfinished projects, I thought it was time to make steps at starting another.

Eldar are a classic 40k race, and can be made to be infantry heavy, which is desirable for this project. I have often admired the early "banana head" look of Alaitoc eldar (blue suit, yellow head), and desire to replicate that for this project. I will be using some vintage metals, some more recent metals, and plastics, all mixed together in a hopefully harmonious way.

Given the notorious difficulties of painting yellow, I thought it best to test out the base color, so as to avoid headache later. I primed these test heads with white gesso, painted the face plates black, and then painted each one with a different first coat, before overlaying with Vallejo Deep yellow (70.915).  I actually like the look of all of them, which is good, but does not make the choice of undercoat easier.

So dear readers, which do you like better? 1, 2, 3, or 4?