Is it good to take stock of our sin? Should we meditate on it and measure it against God and against the sins of others? Is it right to pay that much attention to sin? I think the answer is both yes and no, depending on how you do it.
Measuring Against God
The kingdom is given to those who are poor in spirit, humble, broken, mourning, and contrite over their sin (Matt 5.3-5). This only comes from rightly evaluating yourself before the throne of a holy God. Before we find any good in the gospel, we must find the bad (Is 6.1-7; Is 66.1-2). God is holy and we are not. Our sin, measured against his purity, means we are filthy before him (Is 64.6).
Measuring against God is a good place to start. It makes us realize our need for a Saviour who will take all our sin and pay all our guilt (Is 53.4-6).