I'm honestly really torn. I think I err on the side of the orchestral version though. For me, I guess it all really depends on the mood of the level and if it is more Contra-esque or Castlevania-esque. All the tracks in this thread so far are good in their own right and are actually some top-notch arranges. Sidenote, you should do a remix album of Castlevania tracks and go through distrokid to publish that shit because your production skills have drastically improved. I could make a few mixing critiques on levels but it's very, very minor nitpicky things. Not that I am an expert on mixing anyway.
So, to summarize, why not give the player the option to do both straight metal and orchestral also? But if I had to choose, I'd say orchestral.