I use blockchain bitcoin online wallet, because this is my first bitcoin online wallet since i still new about bitcoin. Actually i also have another wallets, but i never use it anymore.
Yes, blockchain.info is the best online wallet and has very high security measures to protect your bitcoin from been stolen, I had used it for some time but hard to switch over to blockio because they found the later to be more simpler and convenient as per my personal needs.
I use their service also. I like it and never had any problem with them, I'm almost 1 year using their wallet. Anyway I don't let there high amounts of money, just for prevention. But for newbies I really recommend blockchain.info, very useful.