That having been said I still prefer large race shadowknights for their melee abilities. If popularity is the decider then troll's are clearly the winner here. There is an old saying however that if a million people believe a dumb thing that it is still a dumb thing. I wholeheartedly agree with this. In my opinion the choice of large race shadowknight depends on your personal playing style.
Trolls make better soloers because of their natural regeneration.
Regeneration can cut downtime in half when soloing. Trolls suffer from a critical weakness to fire starting with only 5 fire resistance. It should be noted that your party members pay this penalty for you when in a group which all but eliminates the problem so long as you aren't soloing. In my opinion ogres are the better choice in a group however. They have naturally higher strength, stamina and intelligence which are perfect for a shadowknight.