Nonmetals are the only elements capable of forming covalent compounds. With the exception of hydrogen, which only needs 2 electrons in its outermost shell in order to be stable (complete its duet), all other nonmetals that react to form covalent compounds do so in order to complete their octet.
So, the first rule you need to go by when trying to decide whether or not a compound is predominantly covalent is to chewck for metals.
Since nonmetals are the only ones capable of forming covalent compounds, any compound that contains a metal and a nonmetal will not be considered covalent.
In your case, cobalt (II) fluoride,
The only covalent compound in your list is sulfur dibromide,