Basically all forex brokers reliable. They are run to business seriously and have intention to paying withdrawal request. However, some broker run with small capital which not enabling them to pay withdrawal in high amount. If we are trade with high capital, better we choose to trade with brokers which technically, being regulated and give assurance that traders capital safe though unexpected thing happen and brokers going down.
I don’t think; all FX brokers are reliable; there have lots of market makers broker are available here & there! So, traders should select their brokers carefully.