AAPC and AHIMA are great, but they are not the only ones out there. AHIMA has been around the longest (since 1928). They initially specialized in health information technology (HIT) and then, hospital coding, however they do offer physician-based coding certifications as well (namely CCS-P and, the less intense, CCA). The AAPC is the largest network of physician coders with over 110,000 members, to-date. Their membership benefits are quite extensive and they are highly recognized in the physician-based coding world.
You are definitely taking the right first-steps to shop around. Since you are just starting classes, keep shopping - see what else is out there and detemine which one works best for you. If your ultimately seeking certification, see which one administers the credentials you are looking for [or potential employers in your area are looking for] as well. Note: Every organization has their own set of letters that you'll append to your name after earning their certification. You may also want to consider how the organization's exam is administered so you can factor in any additional costs the you may incur (e.g. travel, lodging, etc).
Other organizations to research include ARHCP (Association of Registered Health Care Professionals) they administer the RMC certification (Registered Medical Coder) and the exam is administered on-line, and PMI (Practice Management Institute) who administers the CMC (Certified Medical Coder). Also keep in mind, all organizations offer certifications in more than just coding so you may want to look at that as well if you are planning to grow in the industry.
The decision is yours and as you get further in your career, you may find you're a member of more than just one. As an educator, I am a member and/or certified by many organizations (3 of the 4 listed here)...and there are even more out there depending on your ultimate specialty/focus.
Hope this helps!
Jennifer Donovan, RMC, CPC, RMM, RMA