Depends on time of day, instrument and if you have an account of above $100 000. However, their base spreads are shown here: https://www1.oanda.com/forex-trading/markets/live However, they will vary depending on if you look at the page when the liquidity is good (US markets open) or not (mostly asian market hours)
Choosing a broker, we are based on criteria that are generally available, but we also need to pay attention to small nuances.
If it's tight spreads you are looking for in a broker, I suggest FP Markets. I currently trade with its raw account, the spreads average around 0.3 pips or lower, and it is stable even at high volatile market movements.
The broker is reliable and safe, one that does not hide information about, makes it possible to fully understand all the conditions for the client.
Turnkey forex is also good. Been using them for years now and quite satisfied with their Ecn account.