I am taking MGMAT on-line course right now. I highly recommend it as instructors are very knowledgeable and are willing to spend extra time after class to address any questions. MGMAT's quant books are very helpful for people who haven't been exposed to math for a long time. Their SC book is simply priceless (there is no other SC prep book that comes close in quality). I find MGMAT's Challenge Questions archive very useful for quant practice, too.
MGMAT usually offers your first on-line class for free, so you could try it out and make an educated decision on your own. Also, if you participate in MGMAT's orientation session, you will get a $100 off your on-line class.
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