For me, there is no specific currency pair, but I can say it is the Japanese Yen pairs. I am focused on this currency and traders all the pairs in which the yen is included, but mainly USD/JPY, EUR/JPY and GBP/JPY.
I like a more dynamic trading style and the Yen pairs offer that volatility that can satisfy my trading hunger.
On the other hand, for me, the EUR/USD pair is quite boring to trade, even though for others out there is the most profitable pair.
So, it depends on your personal preferences and trading style.