After scouring the forums and the MODDB page, I have figured out and compiled the basic ideas of each titan. I made this as a reference, so that no one thinks the CSO or something else is the titan.
NOTE: all titans are WIP, thus all of this is subject to change, I will update accordingly assuming the thread is not buried and forgotten, but I might bring the thread back to life depending on the circumstances
UNSC Infinity
The UNSC's titan, this ship eats others for breakfast from what I have heard, defying the UNSC's usual philosophy of capitals being simply upgraded cruisers. This ship will be the perfect addition and flagship to your largest UNSC fleet, back it up with some Autumns and you will be good to go. It will also house a advanced compliment of fighters, giving it a even more deadly presence in combat. Some weaponry the vessel is armed with includes Onager's, PDG's, MAC's, and several types of missle batteries.
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And Credit goes to the didact for this awe inspiring model.
Super Destroyer/ Covenant Battle ship
A very dangerous ship, capable of destroying entire fleets if used right. But don't get me wrong, this thing is not a kill-all ship, it will need backup, as it is planned to be nothing than an upgraded cap ship. But if it's backed up by a small fleet, this ship will tear down anything thrown at it. This is all in part from its powerful weaponry, its arsenal includes several energy projectors, plasma torpedo launchers, and plamsma cannons.
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Mantles Approach
Not to much is known about it at this time. Being that the forerunners are nothing but a concept right now. It will more than likely be the toughest ship in the game, as it absorbed multiple SMAC rounds in Halo 4.
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Again, Credit goes to the Didact for this amazing model.
I hope this helps, like I said updates will happen to this as more info comes our way, but for now this is it.
And if there is maybe something I missed info-wise, or would like some more things added post it below.