You will really want to stick with Sun, unless mabye you are programming on Linux. Then there are some other options...in that case, I still myself choose to use the Sun version. Avoid Microsoft "Java" like the plauge.
The advantage of sticking with the Sun compiler is that you will maximize your portability between VMs. There is no ANSI or W3C Java standard, so Sun really drives it...if you want to maximize compatability, you use Sun. You should also be carefull if you use an IDE (like JBuilder) to be sure it comes with the Sun JDK (Compiler, Interpreter and other tools)...
thanks,
spawngo