Choosing the appropriate firm is often dependent upon the products you trade, the level of service needed or the methodology/frequency of your trading system/style. Guy's who trade pit based contracts like NYMEX or Grains have fewer firms to choose from and pay a bit more in commissions. For all of you an RCG or Goldenberg are perfect. For those who trade decent size or frequency then the use of X-Traders functionality and reliability is crucial and saving a buck or so per contract in commissions is SUPER crucial so I'd opt for Velocity. Guy's who trade electronic products exclusively on longer timeframes or who don't scalp (sic) can be less concerned about commission costs and platform reliability than larger in and out traders. For all of you IB is fine but I'd make sure to have a back up broker as IB's record of service interruptions due to connectivity issues have been well chronicled on this board. Also because of Interactives large number of retail accounts, on days when they are down, good luck getting a service rep to answer your call timely and get you out of a position. Been there and done that. Costly.
i will second the recommendation of Pabst to use Velocity for large position size/high frequency futures trading -- the XTrader platform is the best and the rates from Velocity are good. all issues i have ever had were dealt with promptly at Velocity --- i give them an "A".
Could someone comment on futures brokers with API interfaces? I would like the API to be able to receive market data (bid/ask/last price/size etc) and issue orders directly to the exchange. IB is an example and I would be interested to know some others.