Trading pairs that are highly correlated makes it easier. Such as NZD/USD and AUD/USD. Similar to trading correlated ES, NQ and YM.
I always prefer trading with two currency pairs daily. I select them from the highest and lowest pairs and engage in counter-trend trading. This way, I avoid having to battle with one pair and instead navigate by pitting two pairs against each other. It allows me to manage my remaining funds.
I mainly trade EURUSD because of its moderate volatility and smoothness, and also because of the low spreads at my broker fxopen, which is very important for intraday trading and scalping. You need to choose a broker with low spreads and high quality execution on your main pairs for trading.