Biochemistry, Genetics or Microbiology?

Hmm, it boils down to what you like.

Biochemistry, as the name implies involves a lot of chemistry theory.

Genetics involves a bit more mathematics, such as statistics and probability.

Microbiology is more biology-based. You learn about things that are very relevant, but it far less challenging. If something is less challenging, it means more people are capable of doing it, so you'd probably have a more difficult time finding a 9 to 5 job with this field.

Nonetheless, all three fields are a speciality and require much more than just a degree to start a career.

Genetics was a bitch in my class. Genetics and Molecular Cellular Biology (intermediate level) are often the courses that gives a lot of wake-up call to average biology students, and really get your head preped for more advance bio courses.

If you survived general chem and organic chem, chances are biochem won't be anything too drastic and easier to adapt to. Typical chem course routine. Get the theories, do as many given problems (and more text problems if possible) as much as you can, and you're good to go. A lot of memorizations  and concepts, but biochem is traditionally a third year course and you should know better by that year as to whether you're comfy with chem or not.

One thing is for sure. Nothing to easy. Some may be a little better than others, but you have to give your 100% regardless. 

Well it would be  better for you to know about these courses. Such as genetics is more about mathematics and biochemistry is much bout chemistry so Its mostly will be up to you what will you be interest so choice is yours.