Yes, there are better classes that can make you a better doctor and they are called electives! Your pre-reqs are still your pre-reqs. And maybe some schools might be lazy enough not to check your transcript. But, you cannot count on that, as your chances of getting into med school will definetly decrease (almos to zero). And while many people might have waived specific classes, it is also because they took a similar class that taught the same material. For example, if you are a BME, you can waive out of most bio pre-reqs because you have to take a lot of bioengeneering classes that cover basic molecular biology, physiology, etc...