I was like
WHAT? when I read your post. Last year Polyshrink came in packages of clear, translucent, assorted, and white. I had no clue it had changed this year. I guess it would be a testiment to the white! I have tried all the colors, even black ~ talk about disasterous color!! White does seem to be the best and pops better.
I have used the Stampin Write markers, colored pencils (not our watercolors, something more permanent) sharpies, and our pastels. The only thing I didn't bother to seal was the sharpies. I learned last year that the ink will wash off if it gets wet. My best results came this week when I used my pastel pencils. They are a softer pencil but more controlled (and not the Prismacolors ~ I promise, I will look up the name tonight

) I love them because they are soft and color up to the edge of the color.
And I didn't do Smurfs, but we did do shrinky dinks as a kid ~ Felix the Cat and some Looney Toons. Those were fun too.