Unless you want to convert away from the Z55 suspension setup on your LTZ, go with OEM or Arnott. The fronts on the LTZ are electronic & are 2-stage variable, meaning they are a great ride but are more expensive.
I agree, go with OEM. The current part# for the fronts is ACDelco 580-433 and those are for my 2012 LTZ with the Z55 suspension. Picked them up off Amazon for $231.52 each.