Well if you "will most likely be working in the M&A" at GS this post must be a joke.
If you have to choose between TAS/Valuation/M&A at Big4 and Internal Audit at Goldman Sachs and your target is to do M&A you should probably pick one of those Big4 (I don't know which is stronger in USA)... even if you will probably earn more at GS and this may help to finance your MBA.
I don't really know which choise would help you the most to get into Stern.

To the best of my knowledge, I did not know that EY accepted TAS interns? Many of the full time hires that I know of there are doing a rotation, called TAS +, in which they rotate between audit and TAS work, because they prefer people with Audit experience. But thats all I know of in regards to EY.

m rather familiar with PwC's TS group. They have 3 different groups,: CMAAS (Capital Markets Accounting Advisory Services), Valuations, and Financial Due Diligence. Im not too familiar with the FDD group, but I know Valuations would be your best bet to break into IB since eyou will get some modeling-experience, although maybe no directly relatable to IB work. the CMAAS group works more as of a accounting advisory, you can work on anything from carve-outs, and consolidations to IPOs, etc. There is a lot of writing and research involved. However, I know of a lot of people who interned in CMAAS that got into IB full-time.

I dont know much about KPMG's TAS practice, but Im sure it follows a similar breakdown.