Which to choose:audit,tax or others for articleship?

Hii friends...i have currently appeared IPCC both groups.I am in a dilemma:I am seriously thinking of studying & working abroad once I complete my CA.So keeping this in mind what do you suggest abt the field in which i should do articeship training,since artclshp in tax would not mean anything if I go abroad?And also suggest whether to apply in BIG4 or mid sized firms..