kosatka faster preps = more money
cheat money and buy both for less time
Arcade, becuase kosatka is much more expensive and its far more boring and repeatable.On arcade you can do the heist multiple times without getting bored.(or its just me)
kosatka for money
arcade for fun
If you do it right you can earn upwards of a million dollars per 1-2 hours of work.
Really depend on your level, the casino heist prep is a little bit hard for solo players and slow without 2 player or mk2.
Cayo Perico is inconvenient without the helicopter but easier and faster than the casino heist.
Kosatka is a little bit expensive so I really recommend Facility instead of both of them. The doomsday Act II is the best money-making method with the glitch. And you only need to spend 1.2m for a facility in the Paleto Bay.
Kosatka, imo. You can use it for Cayo Perico ( some decent $$$ there) and for fun. Also there are collectables with the sonar. They aren't expensive, but can give you a decent amount of money.
If you do the Cayo Perico heist as a host and you disconnect your internet when the names pop up (gold) (platinum) you can replay the heist instantly without the preps and you still get the money.