As far as I know Google's 2nd-factor authentication is OK, and in this case there was no problem with some kind of weakness in technologie itself, correct? I'm not using Smart phone at the moment for 2nd-f authentification, but special PC only for making coin transfers and no other purpose. Of course there is no any mobility possible , but somehow I believe that it is safer than nowadays Smart phones. Who knows..
OKCoin allows Google Authenticator, SMS authentication, a password for logging into your account, an extra admin password, email confirmation, and saved withdrawal addresses. All those security features are possible at the same time to protect your account from theft. You should use them, but if you aren't, you'll probably still be safe with two good passwords on the account, a good password on your email, and reasonable browsing habits combined with a non-Windows OS.