If you want an *interesting* major, dont go with bio. Go with mechanical engineering or history. But, if you're forced to settle for a lame bio degree, go for bioengineering or biochemistry, or, on the opposite scale, wildlife ecology. The major differences between the bio majors are on what scale and from what perspective you are studying life. Biology tends towards the macro scale, whereas, molecular biology (obviously), tends the other way. Biochemistry looks at the chemical behavior of life systems and their molecules, bioengineering deals with designing and implementing technology into these systems, microbiology deals with bacteria and viruses, zoology deals with animals, botany with plants, etc etc. Ecology is the study of interrelations of life in its environments.
Degrees like ecology, biology, zoology, and microbiology will tend to be more filled with the memorization type skills that you'll encounter in med school, whereas degrees like bioengineering and biochemistry often involve more technically heavy skill learning, and less pure memorization (which is why many people see them as *harder*). If you want to mirror what you're going to learn in med school, a general bio degree is best, so you can take all different types of classes, like molecular, genetics, immunology, biochemistry, and anatomy. A specialty biology degree is helpful if you are interested scientific medical research (ie: biochemistry, molecular biology, medical microbiology, bioengineering).
Btw, welcome to the forum! Dont take everything here seriously, and dont get stressed out, and it'll be fun.