Morrowind generally has a better story, but Oblivion's has more focus. The world in morrowind is a last larger, but the world in Oblivion just seems richer. Morrowind has more to do, but Oblivion's gameplay is so much better.
Also, Bioshock is so well executed on almost every level. It's hard for me not to put it on a top list
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Chrono1219