Void weapons just help break void shields easier. Other than minotaurs, there isn't anything else with shields. If they had a raid with a void burn modifier, you'd definitely want to use void weapons.

If you plan on getting up close and personal with Minotaurs then definitely void shotty or fusion, I recommend shotgun as it will take down their shield and flinch them simultaneously with the first round and finish them off with the second. Other than that it's kinda irrelevant. If you're referring to solar heavies it just so happens that the 2 best boss dps weapons are solar. Happy coincidence.