Unless the filter does reverse osmosis only then water is very pure. But then no minerals at all. And then minerals are added.
So no filter is better in any way. If ur filter doesnt have reverse osmosis. U might be drinking medicines and hormones and what not from ur soil or tubewell water.
One of the main reason girls having precoucious puberty.
So boiling water kills bacteria. Not the medicines. But it is always better to boil because u may not know when did filter stoped functioning purely or has become contaminated. Butboiling water is like u doing the active filteration by hand. So u know it is definitely good to drink and not cause harm.