International taxation - choosing which firm for exposure?

I wish learn more on international taxation and pursue same as my CA career. Need information as to which big4 is better considering work stress/time and pay wise in Chennai.

I'm a newly qualified with approx 1.5yrs of my articleship time spent on DTAA etc., Please advice me among E&Y, KPMG, Deloitte, PWC or even any other firm which can provide good exposure on subject of interest in Chennai.