Of the choices presented I would have to say Data. It is always interesting to see how similar and yet opposite those two characters are, however. As Spock himself suggests in "Unification" (TNG) their personalities are very similar -- but Data's ongoing obsession with finding the "humanity" he doesn't have is almost the antithesis of Spock's endeavours to distance himself from his own.
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But in all honesty, perhaps I am a little biased because I freely confess I like the 24th century Trek universe a bit more than the 23rd. My favourite character is Julian Bashir, and second is Elim Garak, both from DS9.
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"We're an anarcho-syndicalist commune."