I painted my floor with an QuikCreat Expoy coating. It worked out better then I expected. As previously mentioned prep is the key. The floor must be perfectly clean for the paint to stick long term. I power washed it, used hydrochloric acid, washed and rinced. The paint sticks fine and the price is right. I do have one area peeling near the garage entrance but it's easily patched. Your garage seems real nice. If I could do it over again I would tile it. A dark tile with a grey epoxy grout will clean up easily and have a very rich look. It will last, is repairable, and will add tremendous value to the home. I'm going to tile mine eventually and a scuffed expoxy coating makes a great base for tile to adhere too.