Hello Erica, Great question! The Associate's degree you should pursue really depends on the requirements of the degree at your future University. You want to declare a major that allows you to transfer the most possible credits to your BME program and that provides you with the best preparation and pre-requisites. For example, at the community college I work at engineering student pursue a degree in an Associate of Science. This degree offers a higher level of math and science coursework that is required for engineering programs at nearby universities. It also offers flexibility for students to vary additional coursework based upon the engineering discipline they are pursuing.
Your best bet is to to pull up your degree requirements from the university and take that with you to an advising appointment at your community college. I would also suggest that you verify with the university that your community college degree and coursework will meet the admissions requirement of the BME program.
I hope this was helpful. Feel free to ask me follow up questions and best of luck! Engineering is awesome!