I have pee pad trained mine for almost 11 years now. The oldest started out by using newspaper( I had a dog run over a few years back, so started pad training after that). I find it's much harder, once they've gone outside to train them on pee pads, than vice versa. I love having mine pad trained, I don't have to have any set schedules, etc etc. to me pad training is the way to go...
Plus when its cold or rainy out, I don't have to try and get them to go out, nor do they have that "stinky" dog smell