Criterion for gravimetric analysis of silver
The solubility of $\ce{AgCl}$ is equal to $\sqrt{K_\mathrm{s}} = \pu{1.3E-5 M}.$
The solubility $s$ of $\ce{Ag2CO3}$ is such that  $K_\mathrm{s} = 4s^3.$ So that its solubility $s$ is equal to $s = \pu{1.2E-4 M}.$ This is ten times more than the solubility of $\ce{AgCl}.$
For gravimetric purposes, $\ce{AgCl}$ is a better choice.