Of the two choices put forth, Monarch all day. While I'm not a huge Nikon fan, I do have a Monarch 2.5-10 on a tang/safety Ruger and it's been flawless. Have only had one Vortex (briefly) that was already on a rifle when I bought it and found it to be inferior to VX1s and Revolutions optically. YMMV.
John
