What advantages are there for existence over non-existence?

There is no way to escape the risk of serious and severe harm while living. Pain, suffering, and eventual death are undeniable realities of our material world. However, you can prevent forcing these risks onto others by not giving birth in the first place. 

Most people would agree that it’s wrong to subject someone to pain and suffering without first getting their consent. It isn’t possible for would-be parents to get prior consent from a prospective human as to whether they would like to join this world. No unborn humans can consent to life, desire a life, or have a need for life. Is it ethical to impose something onto someone else when they are unable to provide any form of consent? How many individuals would desire coming into this existence if they could understand the fullest possible picture of what life entails? Would they not prefer that their prospective parents prioritize already existing life in need, or remain childfree due to not having adequate parenting abilities? 

You may be glad you are alive, but you can’t guarantee that a new person will feel the same way.