IMO 3 wasn't much better, I know many disagree but the bad BR, terrible netcode and mediocre launch maps really turned me off at first. Eventually it had a map collection to rival that of Halo 2, but 2 will always be the definitive Halo MP experience, again, imo
"Aren't you the guy that bought expensive HDMI cables claiming cheap ones funded terrorism?" -The Killer 5
3 had the best balance overall, and the MP maps were mostly great, second only to 2's.
4 is a close tie in balance, has a ton more options which I've had fun with, and the maps, while not as good as 2 & 3's are pretty good.
2 has the best maps in the series and good balance for maps, but the weapon balance, glitches and cheapness of BvR and such took away from it for me. I know some people liked that nonsense. I did not.
CE was mostly played between myself, family and friends, but we've probably logged more time on that than any other Halo since and we STILL pop the game in from time to time. Good maps, and pure nostalgia.
Reach had a few fun maps, mostly Forge variants lol and...that's about it honestly.