In case you would like to attack specific bosses...
North Frontier (N-America): Hunters, Scavenger, Predators
South Frontier (S-America): Spirit of Motherwill
Mid-Continent (Europe): LiV
New Frontier (Africa): N-WGIX/v "Black Glint"
Far East (Asia): Red Exusia
South Islands (Australia): To-Bros
Middle East: Grey Lotuses
Keep in mind that you'll only be able to narrow down your choices to two of them, not a single boss. In the event that you're using UNACs, Autocannons are a safe bet, but you will want to go with CEMGs for bosses like the To-bros and the Scavenger-types.
Note that you can cheese LiV with a Grind Blade, and Lotuses, Scavenger-types, and To-Bros can be attempted Solo, though UNACs can be useful too.
Light can be just as blinding as Darkness. Bring some Sunglasses.