The original BioShock was a masterpiece. It's a tossup between it and Super Mario Galaxy for favorite game of last generation.
I haven't played BioShock 2, and I was disappointed by BioShock Infinite, but the original is something I can highly recommend. If you haven't played it yet, give it a try.
Two great games. But while the story of BioShock still holds up wonderfully, the gameplay feels somewhat dated, so I'd give the edge to Galaxy.
Btw, any reason you prefer Galaxy 1 to 2?
TBH, I never got around to playing Galaxy 2. I didn't have a ton of spending money at the time, what I had I was prioritizing on other things at the time (trips to the movie theater and a few DVDs/Blu-rays), and the only new games I bought that year were Mega Man 10 (an inexpensive digital-only release, and the last digital-only title I ever paid money for) and Halo: Reach.
I really need to get a copy and play it.