All of the CRAB drugs (Copaxone, Rebif
, Avonex, Betaseron) are pretty much equally effective
overall, offering about one-third reduction in relapses when compared to a placebo over two years in people with relapsing-remitting MS (RRMS). People with RRMS usually make their treatment decisions based on their doctor's advice and experience with similar patients, as well as concerns about convenience, side effects and cost."
Here is another page from the about.