Halo 2 was my favorite. I've only played Halo 3 during it's prime a few times because I couldn't afford a 360 then.

I loved the campaign and multiplayer online and offline.

Halo 3 to the end the elites are on your side they are the best and there elite minor armour is beast mostly just the helmet but halo 3 to the end.

Well personally from what I can remember, halo 3 was and is still the best halo for me. I don't know why but back when halo 3 was the newest game, xbox was at its best. The combination of an excellent story, and non stop fun multiplayer made it how it is. Still remember playing ghost busters or fat kid on custom games or BTB with a full party. Those were the times.

Reach, it had a great customization, campaign and of course the fire-fights where fun. Also invasion was awesome.

My favorite was Halo 2 on the original Xbox because:
It showed players' emblems rather than clan tags in game
Super bounces
BXR
Double shot
The feel of the sniper
Reloading YYs were very easy
In-game clans

I loved Halo Reach, the best Halo by far.
I find it fun to play a little Halo 4 every now and then but not to brag or anything, I find it too easy online. I always end up on top of the leaderboard and can't find a challenge. Anyone else have this problem?