Go for 6.1 and get everyone in your organisation on the Subscription. That way everyone gets upgrades from then on automatically (with the usual help from your IT dudes with Admin access) and you never have to worry about some people being on THIS version who cannot open files from the other developers on THAT version, etc.
Adobe is putting some [not so subtle] pressure on everyone to go with subscriptions. If you don't obey, and go with boxed editions, it's looking like you will always be one or two steps behind the 8 ball in terms of getting latest patches, bug fixes and functionality. Sad but true.