* 1.2 vs * 1.4 vs *1.6

Which version should I install in a working environment?

1.4

I was running 1.x I went to 1.2 right away and there were not issues. When 1.4.X came out I tested it and there were many issues. I waited more than a year before I used 1.4.X. I am still skeptical about using 1.6.X. I would play with it and it is most likely production worthy but I would still wait a bit.