I have owned 3 properties. The first about 7 years old when I purchased and the second about 30 years old. My current property I bought off the plan.
With the two older properties, you knew exactly what you were getting. You get a building inspection done that will point out any visible problems. You can decide whether these problems are too big to consider purchasing, or small enough not to really matter if the property is right. With my two older properties, nothing ever eventuated from any “problems” found on the building inspection.
Then there is the “new” place. Of course, being new it looks fantastic. Perfect infact. But nothing is ever perfect. With a new building you get “settling” that can result in cracks. May be nothing, may be something. Then you may find other problems that need addressing, usually the week after the builders guarantee has expired.
For me, neither is better. They both have advantages and disadvantages.
I still go by the older (>30yr) property regularly. To my knowledge it nor the building has ever had any major works done to it since I sold it. My current place however seems to have something new to address every week!