Oh I've still got more plays left ahead. I played the first one about 14 times now from start to finish, and I had three different characters. Oddly, I never cared for the soldier class in either game, but in the first the biotics were way better. My good Shep, ultra paragon man of justice, is well, good all the time, the great peacemaker. Then there's my evil renegade selfish masochist Shep, a female, all bad, cruel at every opportunity, likes double-crossing when she can.
My normal Shep I play based on my genuine feelings, about characters, situations (like friendship, bigotry, loyalty to a cause). I really do my best to let go and immerse myself, and with ME and ME2, even if they felt limited in a lot of ways, I was still able to really do that.