I don't think there's anything like a safe broker or a dangerous broker, depending on the person doing the research and involved, If you're a trader then it has been said times without number to basically pay attention to the type of broker you do business, personally infant count the number of times I've drummed this but the problem is many people don't listen, they get burned and they complain.
You should under no circumstances work with a broker that has headquarters in the island countries except Deriv because they've been around for a while and have built a name for themselves, but every other one, you should do your due diligence.
You should make sure whateverbroker you use is located in a capital city and are registered with CFTC, else they might deny a payout and nothing will happen, always make your research before investing your money in a broker, a word they say is enough for the wise.