Copaxone is the weakest and he did not recommend it for me.
Betaseron, Rebif and Avonex are essentially the same drug, Intefereon beta, administered in different doses.
My Neuro is a big believer in Neutralizing antibodies.
Avonex NAB rate is around 5%
Rebif around 10-15%
Betaseron 25-30%
NABs can bind to the active side of the interferon molecule rendering it useless. So naturally (if you believe in NABs) you would likely pick the one with the lowest NABs.