It's really just your preference, however, greenaddress does offer better security and features. Greenaddress allows you to setup a transaction limit and will limit your transaction volume. If your account gets hacked, the hacker will not be able to make more transaction than what you specified. Also, blockchain.info has some security holes before.
Yes, it is 100 time more secure than blockchain.info - check the greenAddress official thread here in the forum : https://bitcointalksearch.org/topic/greenaddress-open-source-multisig-wallet-service-521988
I couldn't find an option that lets user have control over their Private keys, what happens if for some reason the site is down? How will a user get access to their funds?
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But what happens if your service goes away? Will I lose my coins?
GreenAddress signs each transaction with its own key in addition to client-side signing by user's keys, and funds are stored in 2-of-2 multisignature outputs requiring both signatures to spend. The drawback of it is that you cannot control your funds without GreenAddress' signature, so you are right to worry that you can lose your coins.
But! We have solved this issue by providing nLockTime transactions which essentially make deposits 'expire' after some time, which allows redeeming them without our intervention after this pre-set period of time. It is enabled by default when you have email notifications and two factor enabled.
This allows you to keep your ease of mind even in case GreenAddress disappears with its keys.
It also means that every time the funds expire the user has to re-transfer them. This can be automated on login and notified in advance via email or manually done.
For redeeming the funds after expiration, you can use a tool we've developed specifically for this purpose - see Gentle and its project on GitHub. It's open source!
. Therefore, even if they go down, you can still redeem your inputs using gentle(http://greenaddress.github.io/gentle/#/view1) GreenAddress signs each transaction with its own key in addition to client-side signing by user's keys, and funds are stored in 2-of-2 multisignature outputs requiring both signatures to spend. The drawback of it is that you cannot control your funds without GreenAddress' signature, so you are right to worry that you can lose your coins.
But! We have solved this issue by providing nLockTime transactions which essentially make deposits 'expire' after some time, which allows redeeming them without our intervention after this pre-set period of time. It is enabled by default when you have email notifications and two factor enabled.
This allows you to keep your ease of mind even in case GreenAddress disappears with its keys.
It also means that every time the funds expire the user has to re-transfer them. This can be automated on login and notified in advance via email or manually done.
For redeeming the funds after expiration, you can use a tool we've developed specifically for this purpose - see Gentle and its project on GitHub. It's open source!
