I doubt if many brokers even have a physical presence anymore. Trading for sure is strictly limited to online I guess. But no matter what, trading should always be done via regulated brokers. Precisely why I’m using Pepperstone and Fxview. Both are regulated by FCA besides a host of other authorities.
I think online reviews are a big give away. And so are the testimonials of existing users. Found recommendations of using Fxview, Pepperstoner and AvaTrade on babypips (again a reliable source of getting right suggestions) and created demo accounts of all 3. Found FXview more compatible to my needs and have been trading with them since about a year now. So I believe social trading sites and communities are good resources for validation and recommendations.