There isn't really a data support which side is better. Its best to have baby seat to face backward for most safe position.

If you are travelling on Interstate highways or other higher speed roads, I would think that the chances would be higher of being hit on the driver's side?
If you are in multi lane traffic and travel in the right hand lane, except for passing or exiting, this would also make your passenger side safer? The center might be a good spot because it never gets the direct impact......
Otherwise, focus on your driving task, don't let anything distract you from your attention to the roads. Look and plan your trip well ahead, checking maps, having a good navigator in the car beside you who is good with observing traffic/signs/reading maps, so that you can focus on driving.
Don't talk on your cell phone while driving. Let someone else answer the phone, or pull off the roadway to talk.
With good planning and attention to your safety, (don't pack things to obstruct your line of sight in all windows - nothing in the rear window, etc.). If you have children, stop often to let them blow off energy ina park or at a lake. It's worth it too, because you as the driver also get a break.
Don't forget those eyedrops! The flow of air with windows open or air conditioning on tend to dry out your eyes and cause irritation.
Get lots of rest and sleep. Eat lightmeals. Take snacks. Drink lots of fluids while you are driving too (water is best).
Many things contribute to crashes and July is the highest rated month for automobile crashes. Get off the road before the sun gets to that blinding point on the horizon. This will give you and your family a chance to burn off some energy and swim/bike/walk around the place where you plan to stay.Enjoy your trip!