Sometimes I am open multiple pair on the chart, but most daily trading I like to trade in EURUSD and EURJPY, both pair has a correlation of movement although not the same for safe trading can use for hedging position
My favourite is EURUSD and other major pairs. The reason why I opt for major pairs is because they relatively have tighter spreads. I focus more on trading with tight spreads even if the commissions are a little high.
I stick to EUR and USD because they have always been the best pairs in all the time that I have traded. I tried other paris but he did not work out as I expected so I decided to revert back to the two.