blockchain.info
Fast, easy to use, available everywhere (especially on my smartphone)
Please don't forget to enable a secondary password, two factor authentication, and change your security settings so you get a wallet.dat backup regularly.
Don't lose the URL for your wallet and backup your backup in an encrypted partition somewhere.
Then make PAPER BACKUPS of your Blockchain.info wallet and put those in the encrypted container too.
Make a few copies of this container and store them safely (not all at the same location).
And enjoy!