Both are different, but similar gametypes. VIP is the H3 gametype where the chosen team VIP gets over shield. The only way to score points is by killing the other team’s VIP.
The other is H4’s Regicide, a king will be chosen from each team, similar to VIP. The do not start with overshield, they essentially have a big bounty reward for being killed, and can gain power-ups over time. Killing the king isn’t required to win the game, so the overall objective is to gain the most points.
I don’t mind both returning, but my vote personally goes to VIP. I’ve missed it ever since, and love the idea of 1 person being the absolute primary focus in order to win. We’ve seen BTB regicide in H4, but I will kill to have a BTB VIP. I think a slight alteration to VIP would be needed, like Overshield over the course of time.
I hope VIP returns, but it needs some fundamental changes. There needs to be more of an explanation about the VIP’s job. In H3, sometimes a random would get the honor of being VIP and would mancanon out of the base in Valhalla and charge headfirst into the enemy base. It was so painful to watch! Maybe there could even be some kind of walking restriction, making the VIP stay in the base or something.
Another idea I had, it might be cool to appoint a “sheriff” or “bodyguard” that can earn points for defending the VIP or sticking close to VIP.
Team regicide was fun, but not ffa.
I liked VIP more, but Regicide was pretty fun as well. I always saw it as a mixture of VIP and Juggernaut, both of which are incredibly underrated gametypes that need more presence in matchmaking on the MCC. I always thought the VIP gametype where you had to escort the VIP to a zone to win the round was an awesome idea that I never saw in matchmaking, only in a custom game.
Convoy: Warzone gametype, vehicle centric gameplay trying to move each team’s VIP, which is a special vehicle, from point A to point B. Victory relies on splitting up the convoys into attackers and defenders.
Otherwise, Team Regicide was more fun for myself. I wanted to be #1 because I knew the enemy was coming to ME!!! 
Regicide in ffa was very frustrating. Especially when you were the King and had the max bounty so the second place player could instantly know where you are, kill you and end up winning the game. Then you find out after the game that that player did terrible with a negative K/D and you’re just sitting there speechless.
That being said, at times the gametype definitely had it’s moments of being fun and intense. It was a cool concept but there were mechanics within the gametype that just didn’t work well. My suggestion would be to have the King be worth 2 kills as opposed to one kill at all times. Seeing as though Halo 5 this time around does not utilize the point system for the scoreboard like is was in Halo 4 it would only make sense to have it like this.
The King will still be able to get the power-ups. Another possibility would be to have the King not be shown on everyone’s HUD via waypoint. That was just unfair and was very chaotic because you had people just coming for you and no one else. Seriously, I had 2 players coming at me in a straight line trying to kill me instead of going after each other. It was quite bizarre to see that. Actually scratch that. I think it would be more fair to have a waypoint over the King so everyone could see. It would be more unfair to have a scenario in which you go after a player who you think is just another player in the match but find out he’s the King once his overshield activates out of nowhere. I think that would be more frustrating.
Both would be nice but I’m partial to Regicide.