The highest standard for the age of consent is that there is not one age but a right age for each young adult. This would apply for two young adults of the approximate same age. If that is not good enough for you, then use 18. There will never be a right age of consent for a full grown adult to take advantage of a young adult. But if that is not good enough for you then use 21.
Why not 25?
Why does age have to be approximately the same?
What is a "full grown" adult? (humans grow until they die)
All you have done here is list out your edicts based on your moral views. There is no evidence submitted to support any claim you've made here. These are simply arbitrary limits you've set up based on your own opinion and viewpoint. How are we to believe that you are the one person out of billions on the planet who somehow knows the true moral age of consent? What made your opinion on this so special?
Why not 30? That is the problem with trying to codify morals. There is nothing special about my opinion, boss. Are you seriously telling me that you don't know when you are doing wrong? Are you telling me that you need for society to tell you how to behave. If you are 35 and you are taking advantage of a 16 year old, which society says is ok, do you really believe that is ok?
Open your eyes to what I am trying to say and stop being so argumentative just for arguments sake. You aren't helping anyone by arguing against what is good and just.
I'm being argumentative because what you are trying to say is incorrect. There is no "universal moral truth" that existed before space and time. Morality is a construct of fallible man. It can be rooted in false myths, prejudices, religious teachings, societal status... all kinds of things.
Age of consent is a real good issue in which to explore your argument. If there was some "universal truth" we would know that naturally and that's how we would codify it. Fact of the matter is, people develop and mature differently depending on life experiences. Cultures change with time and societal norms and acceptances change. We go from periods where it's perfectly fine for children 12 years old to marry or even have sexual relations with adults to periods where that is taboo and prohibited. In some cultures, marriages are arranged at birth. There has never been any "universal truth" with regard to this, it's all over the board through the ages.
I get that YOU live in this certain day and age, in this specific slice of time, where you've adopted a viewpoint of what is right and wrong. But you can't be so arrogant as to believe your understanding is some kind of "universal natural law" that can't be questioned. You sound like an authoritarian moralist. I'm not comfortable with you deciding my morals. I'm much more comfortable with everyone coming together and collectively determining (having a voice in) the moral boundaries for the society we have to live in.