As I said, statistically they are nearly identical. That is what the NHTSA CPS curriculum states. At first glance, the driver's side may appear safer, because some people think you naturally protect yourself. But unfortunately you can't predict what kind of crash you'll be in. If someone on your left blows thru a stop sign, you may not even see the other car until it hits you.
We do look at lifestyle issues. If you're in a city and will be taking the baby out on the curbside, it makes sense to have the child behind the passenger. If you are mainly parking in large parking lots, it may easier to have the baby on the driver's side. These are parental "tough choices."
One way of thinking to make the statistical info moot is to think of families with more than one child. Then, unless you have a very large car, usually both children will sit on the outboard sides. Parents don't choose which child to put in the *unsafe* side. And the statistics ARE nearly the same.
Obviously, you want to make the most informed and best decision for your child. The statistics are not significantly different, so you may want to rely on how you use the car to make the best decision for your situation.
Good luck!