Best Supported Brokers

For Futures Auto-trading, has anyone had any experiences that would help recommend or sway away from certain brokers? I’m currently with NinjaTrader, but want to try multiple strategies in multiple accounts and they seem to have a long and negative outlook on this, so I think I should open up an account(s) with another broker.

Tradovate?
Gain/Daniels Trading?
TradePro?