You said three, but I am going to mention four of them that are always useful to me. They are:
•   Bitcointalk.org
•   Coinmarketcap.com
•   Cointelegraph.com
•   Coindesk.com

These are the four sites that I visit regularly, especially bitcointalk.org. There is hardly a day that goes by that I don’t visit the bitcointalk.org forum, I am always coming here to look for important updates and to learn new things as well. Then coinmarketcap.com is another site that I do visit regularly, and I even have their mobile app on my smartphone for easy access to always check my portfolio and know whether the market is on a boost or not. Cointelegraph.com and Coindesk.com are the sites where I read official news about cryptocurrency. Cointelegraph.com can be really interesting as you can find price analysis there. I do recommend them to people.