WE just bought ASA this week, its current version is 7.0. Just want to your opinion/suggestion on what is the most stable IOS for my ASA based on your own experienced and cisco security advisory. Im planning to upgrate it into a higher version since my current PIX is running on 7.2(2) without problem. Im going to configure site-to-site VPN, EZVPN, H323 and SIP traffic. Thanks in advance!
8.0.5 is pretty stable without major issues.
8.2.2 is also stable, with more features and has been out for some time.
Since you are starting now though, maybe 8.3 should be your choice since it has some major CLI syntax changes but also many features.
8.0.5 and 8.2.2 are equally stable and mature I would say.
8.3.1 is good enough with many features and changes.
The release notes for the versions are http://www.cisco.com/en/US/products/ps6120/prod_release_notes_list.html
I hope it helps.