I saw this question asked on the Halo 5 sub reddit and thought it would be interesting to discuss here as well. Basically just say what you would want on the UNSC side and the Covenant/Banished side.
I said for the UNSC I want the Kodak. It would be amazing if it behaved like the artillery vehicle in BF4. War zone would become very interesting with it. For the Covenant I want Vampires. This is a true anti-air and anti-vehicle machine. It would be awesome to see the beam charge up and wipe out a warthog or to see a cloud of needles chasing a wasp or banshee. If I were to choose any other vehicles for either side it would have to be: UNSC: Cobra, elephant (or mastodon), and the hawk.
Covenant: Engineer (only reason it’s not top is because it’s not technically a vehicle in the halo canon, but if we were looking in the context of halo wars, a repair vehicle of some sort like an engineer would be awesome at preserving the life of reqs. You could have a vehicle repair, ammo dispenser for all tiers, and a Spartan healer)
The ability to drop anywhere on the battlefield once a match (BTB only)
Upon dropping, the ODST drop pod stays on the battlefield. This could lead to some tactical cover placements
It would be able to fill 2 niches, and effectively be a covenant combination of the Mantis and the Scorpion. The covenant have lacked a dedicated direct fire MBT and obviously lack a maneuverable walker in the game as well. The size works too because according to online sources, the Locust has a smaller base or “footprint” than a Scorpion and is about the same height as a Mantis.