Blockchain.info is a good wallet if you are a newbie. It is very easy to use and it gives you a little more control on your money than other online wallets like CoinBase or Xapo.
Can you immediately and instantaneously sell your BTC with that wallet though?Im using coinbase, is that good enough for an average user? 
Im beginning to think the title of this thread should be Which Exchange is the most reliable and convenient?
If you are looking to trade small amounts on a regular basis then I can see why you are focused on your choice being an exchange, in that case you have to decide on your own risk level otherwise if you just want to buy/spend/save why take that risk of using an exchange as a wallet?
Having said that as Coinbase started out as a wallet but is now focused on developing as an exchange its probably the best combination of the two but I would at least be tempted to sign up and explore other wallet options to see the extras they offer, privacy, control of private keys etc.
For many bitcoin users decentralisation, privacy and control is the heart of bitcoin.