it depends on the market you are in. Also, sometimes you can get more for your house if you make the right updates and stage.
Often it is less expensive to upgrade your existing home. Especially if you are happy with the basic floor plan and neighborhood. A new home, particularly a custom home is going to be your largest investment. Shop for quality, licensed contractors with a good reputation.
Location, Location, Location. I just advised a client the other day to repair the house and rent it out because the location was questionable. In a nice neighborhood you will see a larger appreciation for with your remodels.
The advantages of a new home are, warranties on everything, better values, insulation appliances etc.
New codes can mean lower insurance costs, lower fuel bills.
Depend the budget.If you have enough money for the dream house the choice is easy.The new houses have usually better floor plan and they are build in modern materials, usually are more thermal efficient .