When using balanced antennas such as loops, dipoles, etc. a voltage
balun can be used, however, great detail should be paid to the symmetry
of the antenna and even one leg of a dipole being nearer a metal
building, trees, etc. can effect that symmetry.
When using unbalanced antennas end fed, long wire, monopole, etc. a unun
is better used and will even eliminate most common mode currents.
I think most here really want the Unun ...
Regards,
JS