Plastics for food packaging
This question is a little bit broad, but thankfully, there are many resources available.  

In answer to part of your question


  Which one is most suitable for packaging pastries, for example, biscuits?


The Natural Resources Defense Council webpage Food Storage Containers, they state that the safest plastics are PET, HDPE, LDPE, and PP.

For comparing the various types of plastic, the Plasticology 101 website compares the types of plastic according to:


Temperature tolerances
Clarity
Chemical, scratch and impact resistance
Rigidity
Food contact acceptability
Recyclable material


They suggest that PET, HDPE, PVC, LDPE, PP and PS are suitable for food, but temperature tolerances would be a major factor in what food they store.  Another chemical comparison that needs to be considered for the storage of food is information about the $\ce{O2}$, $\ce{N2}$, $\ce{CO2}$ gas and moisture transmission rates are included in Evergreen's document The barrier performance of common plastic film.

Specifically for biscuits, and any other baked goods, according to sevral websites, it depends on what the ingredients are - things to consider are the dairy content, whether the plastic will react with some of the ingredients etc.