I have been trading GBP/JPY but not able to keep a hold. After reading the suggestion here, I am thinking of switching to EUR/USD.
Major currency pairs are the best for scalping due to good liquidity and enough volatility they provide. These pairs also offer tight spreads which lowers the overall trading costs.
I also mainly trade the EURUSD pair. This is the most liquid pair, while there is no huge volatility here, which allows you to set small stop losses and trade with minimal spreads of 0.01-0.02 with my broker fxopen, which is quite profitable.