As you've discovered, the 1.2 exam is no longer offered, so your choices are 1.4 or 5.0. (There was never an exam for 1.3.)
If you feel pretty confident using 1.3, then you might consider the 1.4 exam. As our
SCJP FAQ indicates, the difference between the 1.2 exam and the 1.4 exam is nowhere near as significant as the jump to 5.0.
On the other hand, if you're starting fresh with exam preparation, then I would encourage you to aim for 5.0, because it has a lot of valuable new features and is the most current.