For day trading ES futures, it seems like my current options would be:
1) AMP Futures with Sierra Charts. Possibly MultiCharts or some other also. But Sierra seems to be really good and fast.
2) Ninjatrader with Ninjatrader Brokerage/Dorman
Yes, those are pretty much your options.
I've been trading with NT7 via Dorman for a year and they are good enough for me. Account management is not as slick as Interactive Brokers. You have to handle more things via emailing forms to their support. Never had any discrepancies in my statements.
You can also clear through Phillip Capital for NT. Not sure if Phillip is any better or worse. I know that Phillip allows CBOE bitcoin trading while Dorman does not (both allow CME bitcoin futures).