There is no one "best" ECN forex broker. Different traders have different preferences, so what might be the best broker for one trader might not be the best for another. That said, there are certain characteristics that most good ECN forex brokers share. These include low spreads, fast execution speeds, and high levels of liquidity.Spreads are the difference between the bid and ask prices of a currency pair. ECN brokers typically offer very low spreads because they don't mark up the prices they get from their liquidity providers. This can be a big advantage for traders, as it saves them money on every trade.Execution speed is also important when trading forex. If a broker takes too long to execute trades, it can cost traders money in the form of missed opportunities or slippage (when prices move against you while your order is being filled). ECN brokers usually have very fast execution speeds because their orders are routed directly to market liquidity providers.Finally, ECN brokers need to have high levels of liquidity in order to provide their clients with tight spreads and fast execution speeds. Liquidity refers to the ability of a market to buy or sell an asset without significantly affecting its price. Forex markets are highly liquid, but some brokers have more liquidity than others. This is something you should always take into account when choosing an ECN forex broker.