[Samba] which version best to use right now?

[Philip Brown]

hiya folks,
I've been trying to figure out which branch of samba is best for us to use.
I read the FAQ, and it seems a little out of date. or at best, lacking in info.
It says that, "The current stable, production Samba server is the Samba 3.2 
branch."

If that is the case.. then why are there **THREE** other branches?

why is there also a 3.3, *and* a 3.4, *and* a 4.x branch?

To give an idea of my criteria: I'm looking for a version that will be part 
of a large-scale server for the next few years, as a member of an ms-windows 
active directory