I still play halo 5 and the games in the MCC often (when it works lol)
Halo 5's warzone has been taking up most of my gaming time since it came out and it's boosted halo 5 up to my favourite multiplayer.
Originally I played Halo 3 semi competitively though and loved the multiplayer.
I still play Halo 3 on my Xbox 360. To me, it's the greatest game ever released on the 360. The campaign is epic and the online multiplayer was incredible.
I have two 50s on Halo 3, both with the required amount of EXP for the rank of General. One of my 50s is a 5 Star General and the other is a General Grade 2.