Is there a recommended Java version for OS X 10.5.X?
Not really. If you have installed everything that Software Update has to offer, you have the best available, which I believe is Java SE 6 to 1.6.0_26 for 64-bit capable Intel-based Macs, from Java for Mac OS X 10.5 Update 10.
That's not a safe version, so best to leave it disabled in all your browsers except during the time you are on a web site that requires it, if you must, then disable it again.
Your only alternative is to upgrade your OS to 10.6.8 or above.