I already have a Questrade account but it is Canadian only.
I recently opened an Interactive Brokers account but the trading fees are too high. I paid $27.50 to buy 6000 shares of TNXP yesterday($5500 worth), and another $27.50 to sell today. Such a trade would only cost $10 each way with Questrade, or even less with a discount US broker such as Just2Trade or Sogotrade.

After a bit of research Schwab, Fidelity and E-trade come up as good options.
But Schwab requires 25k minimum which is a bit too high for me right now.