That depends on the package, the PPA, your need for security, and your tolerance for downtime while you sort out problems.
- The official packages are less likely to create conflicts with other packages that you have to sort out.
- The official packages are less likely to have any security problems
than those from a PPA you know little about. - The official packages are more likely to be out of date, sometimes by years, lacking features and fixes.
- The official packages may not include software you want.
There really is no answer to you question, only a judgement call you have to make.