I don't know which version is the *last* version for 9x, but I tend to stick which the early version 6s for everything. Whether or not it's "good" depends upon what you want out of it. For me, I just want it to play my files without nagging me. Version 6 seems to work for most things, and it's way smaller than the atrocious 35mb download required for the latest version of quicktime.
www.oldversion.com is the place to get all the good old versions of popular programs.