I opened an account at Merrill edge 6 years ago back when the free trades were uncommon. I like illiquid stocks and getting hit with a full commission charge when your limit order gets hit with a single share bid was aggravating. Unfortunately about three years ago Merrill started making life difficult for purchasing what they call penny stocks (this includes LICT at 17k per share). As a result, I’ve moved a fair bit of money out, but haven’t closed the account as IB wouldn’t accept my OTC stocks.
Execution wise, I seem to get the best price improvement from Fidelity, Merrill edge is hit or miss, and TD Ameritrade is the worst.
Overall, Fidelity is my recommendation for ease of use and execution, but they don’t like dark stocks. IB is my favorite for international. Ultimately, I suggest keeping multiple accounts because you never know which stocks will be available from which brokers in advance. But yeah, if you just buy large caps, go with Fidelity.