I just started school to become an MA. Thankfully mine is only for nine months, but it's fulltime. The MIBs (Medical Billers) are in class with the MAs, learning the same things, except one day a week when we split up and us MAs learn the clinical things and the MIBs learn the coding. There are 20 students (all female). 14 are studing to become Billers and only 6 want to become a CMA! I'm thinking my job outlook should be pretty good when I graduate in June.
Billers do make a little more money. I think what you need to do is decide if you'd rather spend most of your time sitting at a desk or up moving around and dealing with people. As an MA you'll be giving injections, drawing blood, doing urinalysis, etc. Is that something you'd like? Or would you rather not? That should be what helps you decide which to take.
At the doctor's office an MA is usually the one who calls you back and takes your history, weighs and measures you, takes all the vitals and tells you the doctor will be in shortly...is that something you'd like to do?