It's a matter of preference. Some people like the front row because of the extra leg room while others will never sit there because you can't stow your bags in front of you (they have to go in the overhead bins when you're in that row). Some people like the back row because you won't get anybody behind you kicking or pushing on your seat and it's close to bathrooms while others will never sit there because you can't recline and for other reasons (far from the front makes some people claustrophobic, too near the bathroom, many other reasons). You need to figure out what's important, if anything, about location within the airlplane and choose your seats accordingly.