Statistically speaking the center seat is the "safest" because it's furthest from any point of impact. That said, the "outboard" (behind driver, behind passenger) seats are not unsafe at all. More important than placement is a proper install and keeping the child rear facing as long as possible (RF is safer for frontal and side impact collisions and that safety never goes away; even adults would be safer RF if that were possible).
That said, until this summer our family's only car was a beetle, which doesn't have a middle seat and doesn't allow LATCH borrowing to install a carseat in the middle, so my kids never rode in the center seat because they couldn't. We placed the RF seats behind the driver since I usually drive and DH is very tall and needs all the leg room he can get. When we had two RF in our car we put the older one behind DH since as kids are older RF they can have their seat installed far more upright than an infant, which helps with the legroom issue tremendously.
LATCH is not safer than a seatbelt installation. It was designed to make installing correctly easier and sometimes it does and sometimes it doesn't. I personally find seatbelt install easier with my radians.
Also, not that you will need to know this for a few years, but there are weight limits as far as using LATCH. These vary by both the manufacturer of your vehicle AND the manufacturer of your carseat, so you need to clarify with both. For higher LATCH weight limit seats you also have to be aware of the manufacture date on your particular car to know if you can use the higher LATCH weight limits in that car. Because of all of this confusion I always just switch to seatbelt installs by the time my kids are 40 lbs because child weight at 40 lbs is the lowest limit I've heard.