Proudest moment started before I even started playing the beta, the beta was available to play for me at 2pm that day, but i worked till 5pm. I get home and my girlfriend has it downloaded and ready to play, but what really makes me happy is when I see I have about 17 messages that all read "PLAY DESTINY" from the members of my Clan. That feeling was amazing.
In game I would have to say, having a 9 game winning streak with my fellow clan mates.
Worst, either being surprised by a hollowed knight while exploring random caves and what not. Or joining a group of randoms in the strike and doing all the footwork.