New Homes
Newly built homes have top quality control standards, new construction techniques, as well as better energy efficiency when compared with older homes. They sometime carry a one year or more guarantee and good investment options. The disadvantage is that though they are less stressful to get into, it is very hard to sell them for a few years (particularly if the builder is still in the subdivision), and the last price is always higher than older home (though they regularly need very little up-front money and many builders will offer thousands of dollars of improvements and incentives).
The neighborhood will not be established, there will be small shade trees like in an older neighborhood, and it will have more of a frontline feel. If you like “new” and “sparkling” like new car, then the clean scent of a new home will be your thing.
Existing Homes
These are owned by property holders who want to sell their homes. They have been seasoned, and may be better built than newer homes. Many people like the fact that they have the charm and history of having been lived in - in fact, many buyers think that a new home is "cold" if it hasn't been lived in.
Their age gives them morality, and they are in well-known neighborhoods with tall trees and reputable neighbors and schools. They may be funky or customized with exciting quirks. These are for people who like "well-known" OR "different."
They are much easier to sell off immediately after you buy one. Many also have a one year guarantee. They may not appeal to people who like being the first in a home or who want one built especially for them.
Which do you like better - New or Existing? People who like one may not like the other, though there are many exceptions who like both.