I use schwab, etrade, ameritrade, vanguard, fidelity (because I have to).

For me, I openned ameritrade originally because it was cheap. As it stands right now, Schwab for me is the cheapest because I’m on cheaper commission structure based on my assets and frequency of trading.

Schwab sometimes stinks if the market is going crazy. The websites come to a crawl. But fortunately, their IVR phone works pretty well even in peak demand.