Halo CE indeed has a great single player mode. Unfortunately it didn't have a multiplayer online :(. That would have been great!!!

Halo CE would have favoured campers too much. The fov was over 100 degrees wide. In Halo 2 they went with a pretty narrow fov, maybe 65 degrees which meant you had to keep turning to see everything thus letting the movement give away your position and cut down on the effectiveness of camping.

I think I should have really referred to the campaign mode in the title. Obviously CE did not have online multiplayer; but the original question was referring to the "epic" scale and size of the levels involved. I also believe many who are referring to the repetitiveness of the library are overreaching.

You mean in your ass?

Halo 3 tops it for me because it has a greater replay value. I do think Halo CE had a better campaign than Halo 2 though.

Halo > Halo 3 > Halo 2

Can't say about Halo 3 since I haven't played it, but for me Halo 2 > Halo 1.
In Halo 2 you fought in many totally different locations, as MC or as Arbiter. Story is better, gameplay is better, maps are better, graphics are better, more cars, more weapons, excellent multi. Only the ending sucks. Halo 1 maps are bigger, but this is not better IMO and you go through many of the maps twice.

A lot of people just don't seem to grasp the original question. Multiplayer has nothing to do with the question.

Half of Halo 1 was going back through levels you already played... I don't see how you can even compare it to 2 and 3... both are much more complete games

I have no nostalgia factor when I compare the 3 halo games, because I recently just bought all of them and played them all for the first time in my life.

I have to agree that the first is amazing with story mode. Halo 3 has an obvious advantage in technology available, but I was really let down by the story. Halo 2 was pretty awesome though. If they made Halo 3 more like the first one, it would have been way cooler.