Any GL4 will be acceptable. Which you WANT to use is a different story. I like Redline MTL, but Synchromesh is also a good choice -- as IMHO is the OE VW fluid.
NEVER, EVER put a GL-5 gear oil in a synchronized gearbox UNLESS the manufacturer specifically calls for it -- which is typically NEVER the case. That includes a lube that has BOTH GL-4 and GL-5 specs on the bottle. If GL-5 is on the bottle, and you use it, you are very likely to be tearing the gearbox apart and replacing the synchronizers.