Personally, My prefered weapon would be a riptide trident. Before you go critisizing me all like wth is this man thinking and is this kid deranged or something, hear me out. Not a lot of people have a riptide trident and don't expect others to have it either since riptide is significantly rare enchantment.
It doesn't do a lot of damage and a diamond axe would probably better for pure melee alone, but if it's raining or you have a river near, you can pull of some pretty good bow shots. I know i'm not really focusing on the trident alone, because I have no favorite weapon. But the trident is a great extension of a weapon. I.e bow shots, 360s, 360 bow shots, retreating, and more. The trident isn't a great weapon for damage and pure melee, that would probably be an axe or sword. But it can be an extension of almost every weapon on the list. (excluding TNT, shield, and flint and steel obviously)