The poll has it right so far. Mass Effect is the way to go. It makes Mass Effect 2 SOOOOO much more enjoyable (not that it's bad by itself). Bioshock is a fun game, but if you already know the twist, it sucks the fun right out of the game.
The DLC for Dragon Age: Origins is hit and miss. You should certainly get Shale and The Stone Prisoner. If you want a lot of gold, also get Golems. You get a Mace that you can sell for over three hundred gold in Origins. Warden's Keep is good for items and it gives you a place to store your stuff, instead of constantly fretting over what to keep and what to sell. Return to Ostagar has some good stuff too. Everything else is personal preference, although I enjoyed them all.
So yeah, that's the order I think you should follow: Mass Effect, Bioshock, DLC.
The DLC for Dragon Age: Origins is hit and miss. You should certainly get Shale and The Stone Prisoner. If you want a lot of gold, also get Golems. You get a Mace that you can sell for over three hundred gold in Origins. Warden's Keep is good for items and it gives you a place to store your stuff, instead of constantly fretting over what to keep and what to sell. Return to Ostagar has some good stuff too. Everything else is personal preference, although I enjoyed them all.
So yeah, that's the order I think you should follow: Mass Effect, Bioshock, DLC.