Honestly, production is probably the first thing I NEED to hear in order to properly enjoy the music. That isn't to say there is only one "style" or type of production that is acceptable to me -but across the spectrum from raw and sludgy to clean and crisp, it must be powerful and full! Metal's strenght(for lack of a better world) for me comes from the power of the music - and shoddy sound can simply destroy or negate that effect.
Sadly, as a fan of Black Metal, this is a never-ending lament for me. I find the raw, even sloppily executed brilliance of classic Venom or Bathory(we never thought the production was bad back then - a little rough perhaps!)infinitely more listenable that 2/3's of the Black Metal of the "second wave." It's a shame really - for often magnificent ideas and creative genius is truly "lost in the sauce" for, as much of this music sound like it was recorded through a walkie-talkie onto a battery-operated boom-box...at the bottom of a well...in a rainstorm...with high winds...
Beyond all that I am a stickler for drum sound(and to a slightly lesser degree vocals performance). I cannot count how many otherwise albums have been ruined for me by weak or thin drum sounds - even within a fairly strongly produced recording. And if the vocals are weak, though I may like the band in general, I find that they don't make the CD player all that often.