Many moons ago I used Ameritrade, then eTrade. Both sucked at trading Canadian stocks. Over the past few years maybe things have changed, don't know, don't care.
I switched to Interactive Brokers a few years ago for four primary reasons:
1. I can trade directly on the Canadian exchanges in Canadian Dollars;
2. They're a discount broker;
3. I can trade futures and options (don't do it much anymore);
4. I can trade FOREX ( I do sometimes)
This is all from one account. However, everyone has reasons they stay with a particular broker. I had reasons not to, especially Ameritrade and eTrade.
Terry