It's pretty difficult to determine which broker is the best for high leverage, because all brokers have their own leverages and some of them don't have leverages at all. So, you should try various brokers and always pay attention to leverages. Brokers always point this information because it's considered to be general. In my opinion, high leverage is such a thing which you should pick on your risk. If you're able to take such high risks on yourself and you realize all the consequences of taking such risks, then just try to find brokers in the internet or on various forums in special branch. Something like that.
In my account only use 1:200, the higher leverage that offers is 1:500, but I see there are so many PAMM trader they like to use leverage 1:100, I just thinking if any trader looking broker with high leverage, they will trade high risk like want to use such trading strategy like as martingale or averaging trading system, because this strategy need make more transaction, high leverage allows them to open orders using smallest margin requirement
I don't think choosing leverage 1:1000 is good for a newbie, even it is useless, and harmful account, because high leverage can lead traders to become greedy, over trading and this is not a good way to manage money in the forex trading market, my broker offer leverage to 1:500, but I only choose leverage 1:200, swing trader choose this leverage is enough.