They are okay. Nice and user friendly. Fees are a bit steep IMHO (unless you’re trading tens of thousands of dollars per transaction).
If you’re an active and experienced trader, there’s a relatively little-known brokerage called Interactive Brokers. They have very nice commissions (0.5 cents per share for U.S. stocks, 70 cents per contract for U.S. options) and you can even trade directly on foreign exchanges.
The catch is, they are nowhere near as user-friendly as TD Ameritrade or ETrade, and you have to pay extra for access to market data.