I finally got round to finishing this a few days ago (a bit late, i know) and i was just wondering what the best approach is.
In order, Awakening should be first priority. Otherwise, Stone Prisoner, Return to Ostagar, or Warden's Keep should be next, as they incorperate directly into Origins. Out of the others, Witch Hunt, and Golems import your character so they have some importance. Darkspawn Chronicles was my favourite of the extra campaigns but has little significance, and I'm not fond of Leliana's Song.
If money isn't an issue then I'd definitely get Leliana's Song and Witch Hunt. I also enjoyed the Golems one and there's a nice callback to it at the end of DA2 if you're going to play that as well. If you plan on playing any of these then I'd do so before jumping in to Awakening to unlock the bonus gear. Above all else I'd say definitely play throguh Awakening, it's tons of content and a lot of the choices you make there will influence your DA2 play through.
Just beware that after you meet the elf in Awakening there's a bug that can cause you to lose all your gear. Read up on it ahead of time if possible so you can avoid the headache.
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