Well you said 2 things:
1) You are still an undergrad
2) You want to be a CPA
MSA is the logical choice. It's shorter, less expensive and curriculum is designed for inexperienced candidates (without much work experience) to get a job in either public or corporate accounting.
MBA does not make much sense. Very few schools accept candidates right out of college, and without work experience, it won't mean much to you nor would it mean much to future employers.
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