Hey bro
OK I chose anatomy and physiology (1rst choice).
First of all comparitive anatomy will be HARD and so is the genetics one with/without a lab... sounds like more work...
anatomy and physiology is more straightforward + you'll need it when you're in med school.
Parasitology is fine too, but I think the anat & phys will help you more in med school and will be more interesting. I took microbiol in undergrad and let me tell you there is SOOOOOOOOO MUCH to remember its brutal! WORSE than ORganic Chem........