I have traded stocks with both Preferred and CyberTrader for over 2 years. I am no longer using Preferred.
Preferred's auto-trades are routed to Knight. Most executions are fast, but can get very slow sometimes. Their platform had a terrible tendency to freeze up in fast markets. Weak customer service also.
Cyber is a first rated broker. Very fast execution and a very reliable platform. Excellent tech support and customer service.
Preferred's auto-trades used to goto Knight. I haven't traded with Preferred since last year, so things may have changed. My biggest complaint about Preferred is their platform freezing up in fast markets. Whenever that happened, their phone lines become all jammed up. You know how that feels.
I used Preferred for about 2 years but am happily using IB since Jan 2002 and IB is awesome for trading( very no frills though in the customer service dept)
The problem I had with Preferred was their 775 trades( now 995). So now you pay an extra 2.20 to get shafted. They are very slow and they are routed to nite and hrzg who always will screw you for a few cents on your order unless its a super liquid stock( but then your order might sit for a minute. Pref knows this and wants this to drive traders to use auto( 15$), its the only suggestion I ever got from them despite several phone calls. I think this is a sleazy business practice and I refuse to be a customer.
Other than that issue I might have stayed there. If you never use the 995 trade they are fine