what is the best paint to use to repaint old crank baits

It is all a matter of personal choice. Most painters on this board use waterbased paints like Createx, Wildlife Colors or just craft paints. Waterbased does not require a sealed(explosion proof) exhaust system like you would need with lacquer or automotive paints and clear coats, which are solvent based paints.

i use acrylic craft paint that you get at Michael's craft store for 50 cents a bottle

its easily to use, cheap, and there are some good colors available.

Createx is probably the safest! Wasco wildlife paint's are also good. I don't have a supplier near and I cant really tell what the color's look like from their website so I stick with createx. If you go with lacquer paint's make sure your wearing a respirator and that you have the (explosive proof,lol) vacuum system....

In my opinion, Createx is the way to go. Their paints are cheap and safe to use. I use auto air also, but certain series of their paints are a little pricey.  

Check Smiths Paints out. Lots of colors including flip flops in water base. Prices not bad either.