My preference for forward is not to fill immediate holes.
My preference for forward is because historically there are much more Elite (ie norris trophy level) defencemen taken outside the top first round, than there are elite forwards (Art Ross level) taken outside the top 10. If you have a chance to go high and the defence/forwards are near equivalent, I always want the forward as getting elite forwards is harder IMO.
Last 30 years
Norris winners taken outside top 10: Karlsson, Subban, Keith, Chara, Lidstrom, Blake, Chelios, MacInnis,
Art Ross winners taken outside top 10: Benn, St. Louis.
Defencemen develop later, and you are more likely to be able to get a gem later in the draft.