I would do the MMR.
I read an awful lot about this prior to both my kids being MMRd.
I think that the evidence is that for the vast majority of kids, the MMR works and does not cause any long lasting ill effects.
There is a tiny risk to the MMR, I don't think anyone denies that. There is, IMO, a much bigger risk associated with not being protected against these diseases. At least one unprotected kid has now died from measles in the UK, and I think it is not uncommon in US communities who won't vaccinate (eg the Amish).
I was unvaccinated against anything as a child, caught measles, developed pneumonia and i assume meningitis, and have vastly reduced sight in one eye. If I were to lose sight in my right eye, I would be registered blind. Incidentally, for those who believe it can be prevented by good diet etc, my parents ran a health food shop.
I also agree that the MMR is far more regulated and tested than any of the singles. Since some of the concern has been over the additives, esp the preservatives, in the vaccine, and these will, I assume, differ depending on what the vaccine is, I think best to go with the highly tested MMR.
There is a very small risk associated with any vaccination, no one denies that, that is why there is a vaccine damages scheme. But to NOT vaccinate is, IMO, far more risky. You can't avoid risk here, you can only minimise it.