Everyone chooses for himself the broker whose spread will suit your trading personally for me, the broker in March has a spread from 0.2 pips quite profitable, because during trading I practically do not feel it.
Of course, I would like to choose a broker where the spread will be as low as possible, despite the fact that it may fluctuate depending on the currency pair.
From my trading experience, FP Markets offer the lowest spreads. It starts from 0.0pips in EURUSD and commission are lower as well.
I'm a scalper trading with FP Markets the spreads are lower starting from 0pips. It is also consistent even during high volatile market movements.
If spreads are the main criteria, check FP Markets. I use them for scalping, and their EURUSD spreads average at 0.0pips for most parts of the day.
I agree with LiamMason, the spreads in FP Markets are lower when compared to other ECN brokers, and it is stable even during high volatile market movements.