Well, I'm far from being so unselfish so as to wish nothing for myself so...
1. Regain my hair in full and never lose it again. (Extremely important for my self-confidence and even a chance at happiness.)
2. Acquire eeexcellent interpersonal skills
3. That no one on Earth would ever be or feel lonely/unloved/ignored.
Sure, I've got more wishes but that would do I think.
1. The ability to reset telomeres to the appropriate length after becoming too short for continual replication or functioning properly. (In other words, "resetting” the aging processes while ensuring the cells do not become too long which may cause cancer as a side effect of this process - however, it should only last ten years and a person should pass away to prevent over population of the earth. I am sure if someone is 60 to 70 or older would jump all over this to be around 20 years old again for ten years - I would and might even consider it now in my 40s.)
2. The ability to completely heal someone of any and all modalities. (This is separate from above since you are ensuring someone is in perfect health for their age - the aging process would remain normal.)
3. The ability to transcend time, space, and dimensions. (Meeting my Goddess or higher dimensional beings face to face would be awesome; going forward and backward in time as “read only” to prevent disrupting timelines would be cool for observing important events in history; and traveling to other worlds in a blink of an eye without dying would not be to shabby either.)
As a personal preference, I would NOT wish for world peace because it would remove the freedom of choice that people should have. People should be able to choose to abide by the laws or not and suffer the consequences if they do not.
Instead, there are plenty of rich people who would want to reverse the aging the process and would in turn become wealthy myself. I would reinvest the money for establishing prevention of hunger, homelessness, etc types of foundations or programs. This way people have the ability to chose for giving their money or not and others accepting help or not for making their lives better.
Also, the ability to completely heal someone who is rich falls in the same category - as above - for me portraying the modern day “capitalist Robin Hood.”
And, by going back in time without having to worry about splitting the current timeline or creating another multiverse / parallel universe would be awesome too - it would not be right for me to disrupt other peoples time-lines for my own curiosity.