I think Halo 2 is going to be met with more anticipation than Doom 3. The latter has this enormous legacy to live up to, while Halo 2 is closer to its predecessor, Halo 1. So it's obvious Doom 3 would be met with more skepticism than Halo 2.
Well, Halo 2 wins the anticipation round in that more people anticipate it. People who anticipate Doom 3 anticipate it HARDER, but not as many people as Halo 2.
But I think Half Life 2 is anticipated more AND has a lot more to live up to than either Doom 3 or Halo 2. Just my opinion.