not exactly the right forum, but oh well.
i chose Halo 2. yes, that's right, Halo TWO.
it had the best multiplayer maps, it had (in my opinion) a great campaign.
^let me explain that. it did just what a sequel is supposed to do: it set up the series for Halo 3. plus, the plot elements from Halo 2 were just great.
but, in all fairness, it's tied with halo 3 and halo 1.
why?
they're all great games.