Depends. PowerDVD is about the last Blu-ray software left standing, and I use it if I want to access the extras on a disc. If I'm watching the main movie, I run AnyDVD HD which allows me to use the player of my choice. JRiver Media Center by itself can play the main movie on some discs, depending on the copy protection.
I generally use MPC-HC. However, any player I use for the main movie must be able to use LAV filters and the madVR renderer. With madVR I can control my HD picture enhancements instead of being stuck with those built into PowerDVD.
However, if you want "simple", go with PowerDVD. Beyond that, it becomes a time-consuming hobby (but the results are worth it, IMO). If you've never heard of LAV and madVR, go "simple".