I use limit orders. I used to do market orders way back when I was young and too eager. I like to buy when the market is taking a serious pounding, and am often surprised at a buy price much lower than anticipated. I don't like the front running, but I don't feel overly harmed by it. I don't like the different levels of quotes either. Everyone should have the same information, and you shouldn't have to pay more for more detail. It isn't clear to me how they rationalize the different levels. It doesn't comport well with the idea of a level playing field.