Both (P)PB (practise personal best) and ©PB (competition personal best) counts but in a slightly different way.
When I ski at my home lake I know that the boat path maybe was not perfect, the slalom course maybe not to RC specifications but we ski, have fun and try to match our PPBs. A beginner who sets a new PPB by running the whole slalom course for the first time is absolutely worth cheering as well as someone who runs 35 off for the first time. And we compete against each other with a handicap system and we brag about our achievements and I am surely proud of my PPB. It counts! But not in a competition.
In a competition, depending of class there are several judges, end course video, gate cameras and the course is measured. If you really want to compete against others, feel the pressure, have a proof of your ability, get into the ranking lists and maybe stand on the podium, competition is the way to go.
The only thing that bothers me is that my PPB is way better than my CPB.
Tsixam