Halo 4 is a good game, but I think Halo Reach is better. In custom game, we can change the weaponry and other things with the zombie, so we can play nice gametypes like fat kid. Also, the matchmaking in Reach was spectacular! I never get bored on the game after I did like 20 matchs. There was also invasion, living dead and action sack in Reach that aren't in Halo 4. The living dead in Reach is a lot better than the one in Halo 4. Also, 343 did a big fault for not putting firefight in Halo 4. It was really nice...
The only thing that is better in Halo 4 in my opinion, it's the campaign. I was really sad when I saw that 343 put the autosentry, the promethean vision and the Hardlight shield. In my opinion, those abilities are for noobs. Also, the guns are too much overpowered. However, the other things are still nice.