the Big 4. The Big 4 consists of EY, Deloitte, PWC, and KPMG.
MBB are all much better than the Big 4. I would also rank several other consulting firms ahead of the Big 4 in terms of prestige. Deloitte is nowhere near the 4th most prestigious consulting firm out there regardless of what they would have you believe. The term Big 4 does not mean "best 4."