I've been having a lot of issues with my spreads not getting limit filled at market prices with OptionsHouse. I suspect they're sending all my orders to the exchanges with the largest rebates (and therefore the least probability of finding a counterparty to my trades), i.e. BATS. I've been thinking about moving my funds to either Tradestation or Interactive Brokers. Which is better for order execution, and should I be considering another broker? I appreciate your recs.