#1 priority getting your vehicle in between the designated lines. Not on and definitely not over.
If you know how to park and want to be as safe as possible, then pull through or back in for perpendicular spots. You are more likely to hit another vehicle or a pedestrian backing out of a space instead of pulling forward out of one. Additionally other vehicles can see you more easily backing into a space than if you are backing out of a space. You can see other vehicles when pulling forward out of a space.
For angled parking, you would have to be brain damaged to back in to a spot if following the correct flow of traffic.
And FFS, if you don't know how to parallel park correctly, either get a vehicle that can do it for you or find different parking that you are able to actually do properly.