Considering the immense amount of options available in Destiny, it isn't too often I get killed by The Next Big Thing, a shotgun I, myself, use. It isn't too often that I witness a Titan Defender throwing down the Ward of Dawn either.
Destiny players seem to gravitate towards the first person shooter side of the game. Rather than test out the variation of weaponry and skills, the way an RPG player would, the majority of gamers grab the most easily accessible, powerful weapons and abilities. These players also tend to stick with those items throughout their entire Destiny experience.
I don't blame players for wanting to be the best and, if it was up to me, I'd make many items equally as deadly so there wouldn't be "overpowered" weapons. The biggest problem with certain popular weapons is their extreme overuse. When you can't complete a crucible match without being slaughtered by the same gun, held by all six of your enemies, there's a problem.
That being said, here are the Top 10 Weapons and Abilities that I most commonly get murdered by when I step into the crucible.