Font Reserve is the one I use. Although slow to launch, 5 seconds on my Mac, it works very well.
Some users don't like the way it copies fonts into its own 'vault', and it has lots of features that I can't really find a use for, such as the Foundry and Specimen business.
Font menus in most open progs (including QuarkXpress) update automatically except for Photoshop and Illustrator can be difficult that way.
DTP is my business - mags, brochures, ads. Classic doesn't crash anywhere near as often as OS9 used to, so in spite of any niggling problems DTPing in X I think I actually get more done overall.