Which is better for high end raiding Frost or Unholy?

[Zargov]

I was in a pug a few nights ago with another DK that was 2 hand frost spec. I'm currently unholy spec. Our  DPS was roughly the same but my damage was higher. His answer to that was because there were times he was lagging so bad he could hardly move.  We both had equivalent gear at the time except for trinkets. I wish I could remember the name of the other DK but I was a tad drunk during the raid lol .

[Ash]

The Frost tree is tuned around dual wielding. I don't know why there is this sub-trend to do 2hander Frost these days. As far as raiding goes, either can be competitive when played well, but Unholy does have a slight edge.