This is like going to a steakhouse and asking for a juicy grilled cheeseburger and them responding "Sir, we are all out of beef, would you like to order some chicken or fish instead?" That's when I sigh and resentfully thank the waitress, walk out the door, and go eat a less good cheeseburger somewhere else.
I don't want either Halo 4 or Halo 5. Halo 4's multiplayer was a horribly optimized mess with terrible map design principles, it really needed to wait for next gen. Halo 5's multiplayer is whiplash inducing and drowning in Spartan Abilities and Thruster Packs. Multiplayer is the primary reason I play so I've been really unhappy. I miss Halo 3 and I miss Reach. There is nowhere to go for an arena style shooter on the console anymore.
As for campaign I'd put Halo 4 miles ahead of Halo 5 in terms of both gameplay and story. Granted I did enjoy the mythic weapons hidden throughout the campaign, that was really cool. But I hate squad mechanics, I hate relying on AI, I hate cheesy one-liners between characters, and good lord the Warden Eternal fights were done to death.
...but most of all I hated playing as someone other than Chief. Halo is the story of the Master Chief, he's like the friggin' Doom Slayer, nothing can ever completely stop him and nothing should. Seeing him have an equal match with this upstart spartan Locke made me want to throw my controller and scream NO. I wanted Chief to fuse his helmet to the floor. I wanted Locke to be humiliated. He's just challenged a hardened vet who has been out at war against a superior force nonstop for nearly a decade and isn't dead yet. There is absolutely no way that Locke should be an even match for the Chief.
Just... it all leaves a bad taste in my mouth. If I had to pick I'd say Halo 4, even with all of it's problems, just because of how much I hate Halo 5's MP sandbox.