Well, Mass Effect obviously gives you two ways to play the game: Paragon (Good) and Renegade (Evil).
Renegade Shepard is oftentimes hilarious with a lot of his dialogue ("Because it's a big, stupid jellyfish!"), but I don't really like a lot of the long-term repercussions and consequences of being Renegade. For example, I finished up a Renegade run the other day and successfully managed to alienate nearly every possible romantic interest on my crew. That wasn't fun. As Paragon Shepard, you can accrue a sizable harem (well, sort of). Pure Renegade Shepard kills off a lot of interesting dialogue trees, but I suppose you could do a mixture of both to keep those dialogue trees open, which is what I'm doing on this playthrough. I'm choosing the neutral options most of the time.
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"I couldn't stand a day without a past or future. I need to live each moment to keep fighting here and now."