What’s the best way to fix a cracked concrete floor?

It would, but no telling for how long. My advice would be to fix the concrete first, then look at installing a floor on top if you still aren’t happy with the concrete. Fixing a cracked, chipped, or marked up floor so it looks like new is very easy with the self-leveling concrete, available in most home stores. A little prep of the existing floor, mix, pour, and level a few bags concrete, and within 24 hours you have a brand new garage floor.

If you decide to go with the wood floor, I would suggest laying 2×4’s on the flat every 16” or so, filling the spaces in between with 1 ½” Styrofoam SM, and attaching the ply to the lumber rather than sitting it directly on the floor. This will make for a warm floor that is comfortable underfoot as well.