I have used IB, Lightspeed, Sierra Charts and TOS. Lightspeed does have instant execution but charting and platform capabilities can't come close to TOS. Their failure to match zero commissions make them unusable for a daytrader. Sierra Charts has the best overall platform but they do not support their program with stock brokers although I am told IB will allow them as a 3rd party app and one person on the Sierra Charts forum says it does work for him/her. I use TOS for stock daytrading because of the platform flexibility; for example you can have up to 32 stock charts on one screen simultaneously and also 32 individualized stock trading boxes pre set with the number of shares you want to trade for each stock on one screen. Their quotes are slow and trade execution is slow but I can live with that. If I have to wait one second for a fill I figure it even out over the long term.