I say serve the highest paying master as long as this doesn't interfere with your professional bearing too much. However if it does, then it's a tradeoff for reaching a higher career point with the odds of success unknown to you right now. What's known, however, is if you decide to move off to Big 4 then your wage instantly suffers a setback and it won't be this easy or even fast to bring it back to where it used to be let alone any higher.

So, please consider your move carefully.