Finishing any concrete basement floor is optional, but epoxy paint offers the best results I’ve seen. You mix in a catalyst, then roll the product on before it hardens by chemical reaction. Epoxy paint is thick enough to fill small cracks, so don’t worry about filling them. The best looking formulations I’ve seen include coloured flakes that come as part of the kit. Roll the epoxy paint onto an area you can reach across, then sprinkle the flakes on while it’s wet. They make the floor look great, hiding any small flaws so they’re less noticeable.