For short-term work any pair will do but preferably one of the majors so that spread is narrow. On the longer multi-day time-frame, if I had to pick one pair it wouldn't be a pair it would be the Dow - I can spreadbet the Dow itself from the UK. It seems that most forex pairs are correlated with the Dow, either positively or negatively so there is little to gain from watching 28 charts when I cold be keying off one. Or am I being naive?..........
EUR/USD is the most traded currency pair on the market, with EUR/USD transactions. The high daily volume of EUR/USD transactions ensures that the pair has a lot of liquidity which generally results in tight spreads. Liquidity and tight spreads are enticing for traders because they mean that large trades can be made with little impact on the market.
Although the broker I trade with Aamarkets offers more than 250 financial instruments, now I mainly trade his most popular currency pairs.
USDJPY. It’s my safe haven. Not been long since I started trading on Fxview and City Index and with both brokers I am as of now only trading this pair. It’s easy to keep a track on because of its positive correlation. But with time I’ll surely diversify.
I prefer trading with Major pairs like EURUSD, JPYUSD, GBPUSD, etc... because I find it more secure than others.