Best Flexi color pallette for printing?

I use the cmyk.swt. Open it and you'll find two blacks right up near the front. Delete one of them and change the other to 100% K and 0% CMY. Save it under a new name.

Then do View->Create Swatch->Current Pallet. Do some judicious text editing and arranging then print this table on whatever media you're using with whatever profile you're using. Now you have a chart of just which color looks like what for that media and that profile.

Most of the vendor specific color charts are in LAB which is not necessarily a bad thing but using the Pantone CMYK swatch table gives at least the illusion of a lot more options, flexibility, and predictability.