There's nothing *wrong* with the big banks' brokerages, except that like everything else they are primarily concerned with the other products of the banks.
I have a small amount of stuff with CIBC Investor's Edge. I like them because it is $7/trade for everyone now, and you don't have to mess with US$ - they automatically convert CAD to USD *at spot* in registered accounts. I don't know why, but they do. So no Norbert's Gambit necessary.
Scotia keep sending me messages about how I can qualify for $10 trades. Gee, thanks.
OP, if you are putting *lots* of money across, and especially if you use margin, look at Interactive Brokers. They have 1c/share commissions min $1 for North American stuff (I forget the max but it's not more than $10), margin is under 2% for CAD and USD I think.
The downside with IB is that you don't get live data for free (you get real time live quotes with Questrade), and they have maintenance fees unless you have more than $100k USD with them. But IF you are putting large amounts over... yeah IB are really good. Plus you can trade on a bazillion exchanges if you want.
OTOH if you are just doing simple stuff, Questrade is still just fine. NA ETFs? Easy. Live data for quotes included, etc.