this really depends on what kind of size you trade and how you execute. Binance futures (their btc/usdt perp) is most likely cheaper if you look at take fee + spread + slippage. Their default taker fee is 4bps (or 3.6 bps if you pay it in BNB). That means you can slip $4 (with BTC at 10k) and pay the same for your exec - but with most sizes you don't slip that much, if you trade small binance is most often better (spread + slippage wise) since the tick size (minimum spread) is 0.01bps instead of 0.5bps. And on top of that you get a massive fee discount.
> I pay a thousand a year in trading fees to my stockbroker in Australia and they don't even offer an API.
I wouldn't compare Bitmex to an Australian stock broker, I would compare it to other crypto exchanges
