Best PvM build depends on whether you're planning to use a bow or javs.
If javs go maxed lightning fury and Charged Strike. Synergize them. Get an infinity on the might merc. Use Titans and Griffins eye. Use Thunderstrokes for your LI's in hell. Thundergods for them too. Razortail the rest of the time. Rest of the gear doesn't much mattet. Just keep your resists up over zero.
If bows, there are several ways to go. Get a Faith and max strafe and put some in freezing arrow, max it if you've got a way to regen mana. Get all the godly gear you can find and with those skills you'll slice your way through the game.