I've seen two neuros. One general neuro and one neuro who specializes in MS and works at the UCSF MS clinic. Both liked Avonex and had had good experiences with their patients on it. Both felt that the research favored Avonex overall, although they agreed it's hard to tell because there's a lot of information out there. So, based on the both of them recommending Avonex, I'm going that way.
That said, if I find I just can't tolerate whatever side effects I have, I'm going to try Copaxone. A friend just went on it because her neuro recommended it due to the lack of side effects.
I watch my husband shoot himself with Enbrel once a week for his psoriasis and psoriasis-related arthritis. We're a very needly family here. So shots, even daily ones, I can get used to. Losing a day a week to flu symptoms doesn't sound so great, so we'll see.
Remember, if your son doesn't tolerate Avonex after a sufficient period of time, you can switch to something else.