What is the best discount stock brokerage for trading mutual funds?

I signed up for optionshouse.com and tried using the virtual trader to trade mutual funds and it seemed pretty strange. It is my first time investing and I have already done all of my research and know what I would like to purchase. I've looked into TradeKing and Scottrade. I can't use e-trade because there are penalties for not being extremely active and I am using a long-term buy and hold strategy. Thanks for the help!