10.8 and forward have serious problems. But old versions are totally unsupported in terms of security fixes. So if your computer is being used to access the In

10.8 and forward have serious problems. But old versions are totally unsupported in terms of security fixes. So if your computer is being used to access the Internet in general, you really need to be on 10.9 or newer. And it won't be long before Apple stops pushing security fixes to 10.9. There's no LTS equivalent of OS X. There probably should be, but it's a consumer OS so Apple has no real incentive to do that.