Here is a quick comparison of 4 popular silver holos.
These are the 4 polishes used in each pic:
Pointer - Layla 01 Mercury Twilight
Middle - Color Club Harp on It
Ring - Jade Psicodelica
Pinky - Kiko 400 Steel Grey
In the sun you can't really tell the difference between the first 3 polishes. But I think Layla 01 Mercury Twilight is little more grey, Color Club Harp on It is silver/blue, and Jade Psicodelica is a soft, almost sheer holo.
Indoors Layla 01 Mercury Twilight is a flat holo/not as shiny as the others, Color Club Harp on It is a bright silver holo, and Jade Psicodelica is still a soft, almost sheer holo.