Your best choice for Limit on Open or Market on Open + Limit on Close or Market on Close, orders + low commissions will be at:
www.interactivebrokers.com
Good Luck.
What will bring better results for Daytrading? :
1. Limit Orders ( Sometimes will not get you in and will be out of your trading plan)
or
2. Market Orders (pay a few cents more, specially for large orders)
Thanks for helping.