All depends on your particular pants. I regularly switch a front-pocket version between front and back pockets. I have one pair of jeans my wife bought me that has a wide, flat front pocket, and the Plus works better than a Front.
Some slacks tend to have shallow rear pockets, and extra-deep front pockets.
As a general rule, the Front pocket works just as well as the Square pocket in the back, so on one hand it's more versatile than a Square pocket. The advantages of the Square pocket is it does a better job of mimicking a wallet to an onlooker, and allows for the spare magazine.
What do I prefer? Since I'm spoiled, and get to use both, if I'm going to be standing/walking most of the day, I will use the Square pocket. If I will be spending most of the day sitting or driving, I will probably use a Front pocket.