Halo 2 > Halo 3 > Halo 3 ODST > Halo Reach > Halo CE
Based on campaigns.
And it was great.
My Halo 2 disk is faulty, it cant load levels independantly, to play you must start from the beginning. So I played throughnthe entire Halo 2 campaign today. Took about 8 hours but it was great, especially the last few levels. My new favourite Halo game, its just fantastic.
Afterwords, i went straight onto Halo 3, and continued the story exactly from where i left off, almost as if playing the same game, and while jt is still grea and my second favourite Halo, there are some inconsistencies, such as the brutes immediately getting power armour and becoming easier to kill.
I know it is a little sad. but i had a really fun day i must say.