Evolution is a great system for incremental refinements, but it's not very good at drastic changes, and can leave behind a lot of inconvenient vestigial elements. It's also rubbish at dealing with changes on the short scale (such as hairless apes going and building an agricultural society).
But let's say we had a wizard (or a sufficiently advanced technologist). Looking at present-day society, the wizard is pretty happy with how things are going, but wants to file off the rough edges. He has decided to go straight to the source and redo a human being from the inside in order to make a creature that can live more comfortably in the conditions of today. While the wizard can set up whatever he wants inside the body, the result must be biologically feasible - capable of living, reproducing, and so on without magic. The wizard will create a few thousand such beings.
The wizard might look at factors like:
- Viability later in life. For obvious reasons, natural selection does not care much about what happens to an individual past breeding age, but in our society such individuals still hang around, and the physical and mental decay that occurs in old age might be somehow avoided.
- Food consumption. Prehistorically, gorging yourself in times of plenty helped survive in times of hunger. In a society where nutrition is plentiful, the body's aggressive desire to stockpile fats and carbohydrates is detrimental to society.
- Physical size. Being large and in charge was a very useful trait up until airlines started cutting down the size of seats. In a society where warfare is done by machines rather than muscles and lots of people are crowded together in cities, a smaller humanoid might be at an advantage.
- Temperature control. Sweating is really not a great way of getting cool when you're trying to coexist alongside crowds of people in close proximity. Would it be preferable to become reptile-like and not feel hot or cold at all?
- Senses. On the streets of New York, the sense of smell is more detrimental than anything, but walk through the door of a restaurant and suddenly you're glad to have it. Is there a way to take away the bad but keep the good?
The wizard could probably use his fiat powers to improve human society to better fit the human, but let's assume that Reed Richards is useless and the wizard is too much of a mad scientist to do things the boring, political way.
What does the ideal humanoid for the 21st century - or something close to it - look like?
Edited in response to answers: The wizard does not want to make society a kinder, gentler place to live. He likes society. Maybe he is an objectivist, and does not want people to like each other more, or to be less competitive. He just wants a humanoid being who is designed for the needs of a modern metropolis, not the African savannah of yore.
Nor is the wizard intending to replace the human population. Let's say he's making only one thousand of these humanoids, and seeding them all over the world to lead ordinary lives (as a test run, as spies, on a lark, etc).