I have both the brush and pen liner from CLIO. Prior to using CLIO, I was using Revlon Colorstay for over a decade. CLIO's pen and brush liner seem to have the same formula--mostly waterproof, doesn't budge, and slightly wet-looking.

The brush liner is much easier to use than the pen liner. The tip is softer, thinner, and more flexible, so it's much easier to put down a precise line. If you like putting on thick eyeliner, then the brush liner might take a little longer than the pen liner, but the brush liner is much better at giving you crisp, tapered winged eyeliner.

I have oily eyelids and I live in an arid climate. After going out in 100F temperatures, my eyeliner didn't budge even after 8 hours of wear.