Depends. Fish oil is good in small amounts for epa/dha but should not be used as a macro, stick with 1-4 grams of epa/dha. If your oil is 50% epa/dha: 2-8 grams oil.
Flax is good for a macro but many prefer a more balanced oil like UDO's or hemp.
In short, use fish oil for epa/dha and a suitable balanced oil for macro needs.