Well, this primarily depend on your budget
First, I strongly recommend you put more effort on using Google to find out about the available market data providers, and then search for review about them
To summarize what I know about data providers so far is
- Some data providers provide historical data only
- Some provide both real time and historical
You should ask about the granularity of the historical data
-How far back do they have end of day data (end of day data means one record per day which include the Open, Close, High, Low prices)
-How far back do they provide one minute data
-How far back do they provide tick data
From what I've seen, most provider have so many end-of-day data, usually only one year tick data, and on average 3 years of minute data
Some of course have more, some less
When checking Real time or streaming data
- you should check if they provide level 2 data
- You should understand what is level 2 data and if you need it
Generally there is also the question of filter and unfiltered data
Some provider filter their data, some say to provide raw data
Personally i dont really understand the difference, and i have seen so many arguments online that favor both, so i really cant tell which is better (maybe other more experienced trader can inform you more about this)
IQFeed, is generally regarded as the best provider of data for retail trader, they cost around 90 USD per month
There is also many provider who cost around 500 USD, for example Nanex (nanex and iqfeed belong to the same parent company) and dxfeed (dxfeed seem interesting but they are a lot less popular on this forum than nanex for example, so i would be skeptical about their quality)
many brokers like Options Xpress and TDameritrade allows you to access their data streams programatically for free if you have an account with them, you should surely check that too
And there is also the question of how will you consume the data feed?
- if you will use excel, you need to make sure the add-in you will use or know how to use support the datafeed you will subscribe to
- same goes for any other software you plan to use, like sierrachart or multichart, you need to know the datafeed they support
- if you will program your analysis, you need to know about the available APIs, many providers offer C# only
Also its not 100% accurate that blomberg provide the best data
This basically sums up all i know about this topic