Would you rather lose all of your old memories, or never be able to make new ones? Why?
A second reading of this question would be that, if do you think that it's better to lose the old memories, it would mean that your life is deeply-rooted in your past and you're afraid to face the future.
On the contrary, the other option it would mean that you prefer to forget the past. Forget who we were and, in some way and just as ballboy said, who we are...
I'd rather lose my memory than not be able to form new one. If I cannot memorize my past, I feel I just start a new life like a baby, while it's really helpless if I can never remember happy moments beforehand. If that is the case, I would not fight for my happiness because it is always short.
If we had to choose from the options above, I would opt for the latter given that our old memories make us who we are and losing them just leaves us alone with an aimless life to live.