1. Loreal and Mac both have different foundations so which ones are you specifically looking at?
2. It depends on what you're looking for, skin type, how well shades match, is the finish well suited to you, the list goes on and on...
There's no one be all end all definition of what foundation is better than the other, the closest thing you could ask is "Which foundation is better for myself." And you're not giving us any information to really work with.