It looks like metallic silver has been done by quite a few brands, doesn’t it? When it comes to grays, though, I don’t have nearly enough to give a particularly great comparison, but of the three darker grays I own, there are more differences between the three than with the five silver shades.
DUPE ALERT! The first five shades are all quite similar: Milani Silver, L’Oreal HIP Silver Lightning, Make Up For Ever #8L, Urban Decay Dime, and Guerlain Silver . L’Oreal HIP Silver Lightning and Guerlain Silver is are a hue darker than the other three. Make Up For Ever #9L is the lightest of the five.
Product Formulas/Wear: I have no notable issues with wear with any of these formulas (with the exemption of Guerlain’s Stylo Yeux, which I have not tested). They all wear all day for me (tested for at least 12 hours) without budging or migrating. L’Oreal HIP and Milani are the creamiest, with Urban Decay’s 24/7 Liners following shortly after (still creamy, though). Make Up For Ever Aqua Eyes are firmer but still doesn’t tug on the lash line. CoverGirl Liquiline Blasts sometimes need a second pass for true color pay off but otherwise wear fine.