Which of the following are better leaving group than

Which of the following is better cooking ?

Which of the following is better fuel ?

RS^(Ө) is a stronger nucleophile and a better leaving group than RO^(Ө) . RS^(Ө) is a weaker base than RS^(Ө) .

RS^(Ө) is a stronger nucleophile and a better leaving group than RO^(Ө) . RS^(Ө) is a weaker base than RS^(Ө) .

Which is the best leaving group ?