All I can say when it comes to order flow I have tested by placing identical orders at firms and almost always get a faster fill (1000 shares or greater) at IB than the other firms I've tested against. For market orders, there is no contest. You will get abused if using market orders with a firm selling flow. The IHS Market figures should be no surprise. There is a reason the HFTs will pay a few pennies per hundred shares and that's because they are taking so much more out of your pockets.
Net US Dollar Price Improvement vs. Industry Bid / Offer 1
Net US Dollars
(per 100 shares)
Interactive Brokers $0.58
Industry $0.06
IB Advantage $0.52
*Based on independent measurements, IHS Markit, a third-party provider of transaction analysis, has determined that Interactive Brokers' US stock price executions were significantly better than the industry's during the second half of 2018.