One of the most difficult thing is to judge yourself. The main reason is not that you might judge wrong or biased but the problem is then if you overjudge yourself i.e yu rate yourself more than you deserve.
I would rate myself a step below than all my PSAs do because I believe nothing is best and sky is the limit so there is always a scope for you to improve and this prospective of yours will help you achieve more heights in the work you are doing.