FIX API Traders

Looking to move off retail platforms to trade via Fix Engine as sick of getting profit stolen by violating agreements.. (scalping, arb, hft ect.)

1. Seeking good fix providers, deposit requirements for each and what dc they located
2. Advise from any other fx fix traders
3. Looking for examples of execution and slippage on trades
4. Seeking good fix clients with gui

Hoping people with experience can assist

I don't have too much experience with different brokers. But, Interactive Brokers have the fame to be the most reliable broker. As they have an API, they have a lot of HFT, scalpers, etc. But they offer a GUI too.