A quoted spread is only one part of the cost of trading forex. The account type, instrument, session, liquidity and holding period can all change the amount a trader pays.
Spread versus commission
A tighter spread may come with a separate commission. Compare the all-in cost for the position size and instruments you actually trade rather than relying on the marketing headline.
Overnight financing
Swap or financing charges matter for positions held beyond the trading day. Read the broker's instrument specification and check whether triple financing applies on a particular weekday.