What I know now is that not forgetting is the best part. It is the worst part if you don't let the power of the atonement work if your life though. If the process ended with you forgetting all your sins then you would never be able to learn from them and the same temptations from Satan would work again, and we would keep falling into similar traps. We need to learn from our mistakes, and know are weaknesses and strengths, in order to grow after (through the atonement) God has forgiven and forgotten (not going to hold those sins against you in judgement).
For me the best part about remembering my sins is that I remember how I felt burdened by them and guilty for what I had done. I felt that I couldn't be loved by God for the things I had done. I would go to sleep at night in tears just begging to forget cause how could I think I was a good person if I knew what I did. I didn't realize just how selfish I was being at the time, and no wonder I wasn't reaching the last step of the atonement. I had done everything I needed to do: I recognized the sins, sought the bishop to confess my sins, sought after the forgiveness of God, I changed my thoughts and actions, but even though I had done all that I missed the most important part. In D&C 19:16 For behold, I, God, have suffered these things for all, that they might not suffer if they would repent.