Reach had good campaign gameplay, customizable firefight, amazing custom games and forge, and a controversial matchmaking. I liked it all, but some people may say no. The anniversary map packs were the best thought, and tu ctf on breackneck was awesome like in halo 2.
But I feel destiny will knock halo out of the arena for sci-fi immersion. Though, to be fair, writing hasn't been Bungie's strong-suits.
Who can forget the horrible line from halo 3? :
"Ma-am? Alpha aquad is requesting a rendezvous point. Where should we send them?"
*keyes breaks out magnum giving the marine a half look over the shoulder saying in a deadly tone "To war"
I was expecting the guy to pause and respond "...no really, where?"