Riptide is a very unique fusion rifle and I don't see why people complain about the drop ratio. People seem to compare Riptide to Edge Transit, but Edge Transit had nothing special about it in perk combinations. Also you can just delete the weapon if you have the roll.... legendary shards.
Riptide PVP - Under Pressure or Perpetual Motion and Successful Warm or Golden Tricorn.
Riptide PVE - Autoloading Holster and Chill Clip or Vorpal Weapon.