Atoms having equal or nearly equal electronegativities are expected to form what types of bonds?
These are expected to form covalent bonds.
By definition, electronegativity is conceived to be the ability of an atom in a chemical bond to polarize electron density towards itself. The elements on the RHS of the Periodic Table as we face it, i.e.
Nevertheless, electronegative atoms that bind together tend to share electron density equally. This is the very definition of a covalent bond:
Consider the oxygen molecule