Despite being right handed, it feels more comfortable to place my phone in my left front pocket. Maybe because having a wallet in my right pocket predates using mobile phones. What feels most natural for you?
I specifically moved to using my front pockets for everything because of being worried about pick pockets. I find myself guarding my front pockets with my hands in public. It is also a good way to make sure I have everything I need before leaving the house. If there isn't something there pressing on my legs, something feels off.