For one considering a future as a surgeon, which would be the best option: AP Bio or AP Chem.

I can only choose one, so which one is best?

AP Chem would be more beneficial. You need to still take chemistry over in college, but having had seen it before is going to help. edit. I am not a physician but my ex is.

Have you taken all of biology, chemistry, and physics in high school?

Pre-meds in college need to take all of these in college (if skipped with AP credit, medical schools tend to want to see more advanced courses substituted for the skipped ones). Having had all of the sciences at least at the high school level will be helpful when you take them in college.

Assuming you have already taken a year of bio, chem, and physics, it does not matter if you take AP Bio or AP Chem. Take the one that has the better teacher/has better AP results/some other parameter off your choosing.

Be aware though, for most med schools, AP science credits cannot be applied to the med school prerequisites, so you will either be taking intro bio/chem in college, or taking advanced classes to meet the prerequisites

The difficulty of each class certainly depends on the rest of your course load and how much time you have to spare. Chat with friends and other people who have taken each class and get intel regarding how time-zapping each class is.
How have you faired in past AP classes? What is your GPA? Why take them both one year, why not one each year, if it is senior year and you want to get them before college science, that makes sense.

Pros: Good knowledge before you enter premed, very good course rigor before college, topics in class are generally pretty fun.

Cons: Very difficult taking both concurrently, take up a lot of time from other ap/honors, could drag GPA down.

What are the pros and cons? Have you done this? What is the difficulty of each class?

I agree…both are helpful…take the one that fits/has a better teacher.

My son took AP Chem last year and it was VERY difficult. His Chem tutor who was also a Chem teacher at a private school and has a PHD in Chemistry from Stanford said that it is the second most difficult AP class that is offered. She also mentioned that most of the teachers teaching this class are not qualified to be teaching it. She has also taught Chemistry at Virginia Tech, so she’s very qualified and knowledgeable about Chemistry. By the way, he scored a 3 on the test. I have heard that AP Bio is way easier. As other posters have mentioned, many schools( Stanford included) won’t accept AP scores. You should just take the regular Biology or Chem class that is offered at your school and get a very good grade.

It makes no difference which you take in HS as both would be valuable for a STEM oriented student. You will fulfill all the pre-med requirements in college, then you have for years of med school before you become an intern. Nobody will know, ask, or care what course you took in HS and you will have covered all the material you need to know during your college/med school years. So take whichever class you prefer, whichever has the better teacher etc.

I assumed that at the OP’s school, as at most schools, one needs to take regular bio/chem before the AP version, so the OP is looking to choose between the 2 AP versions.