you will have to be more specific... what do you trade? do you require charting? etc... Your question is like "what's the best car out there?"
yeah i realized the question was way too general. i'll be trading NYSE equities and i require charting
have you taken a look at Medved QuoteTracker http://www.elitetrader.com/so/?action=view&SR_ProductID=33 http://www.quotetracker.com/ i found it very easy to use so it shouldent be a problem for a new trader.
Yes you can execute orders from the software and no it isent slow for day trading ( look at the 2nd screenshot here http://www.quotetracker.com/screens.shtml). QT only has a few brokers you can trade direct from the software with you can see the list here http://www.quotetracker.com/qsources.shtml the list of borkers you can use is under "Integrated Trading Supported Brokerages" TD Ameritrade is one of them, not only that TD Ameritrade is a QT Sponsoring Brokerage so you get the software with no ads for free.
NinjaTrader is free for charting and analytics connected to your TD AMERITRADE account. There is a software fee if you wish to use to to trade live. More information - http://www.ninjatrader.com/webnew/index.htm