Halo 2 > Halo 3 > Halo 3 ODST > Halo Reach > Halo CE
Based on campaigns.
If you're a fan of halo 3, come on and join our group. Here you can have discussions and find people to play with
Sick of going on the Halo 3 forum and finding no one else there? Tired of everyone talking about Reach? Want to have lively discussions about Halo 3 with other fans? Then this is the group for you!
Bs sure to read the rules of the group article
http://www.bungie.net/fanclub/412744/Group/GroupHome.aspx