I wrote this for the BD Tribune but it was never published so here you go:
This guide will cover the differences between the three chassis and will give you a bit of an insight into the considerations you might need to make before picking a chassis. In this guide, I’ll create a profile for each chassis, highlighting their strengths and weaknesses. The main factors I am going to consider here are; how they deal with nukes and spy attacks, what bonuses they have against other chassis and how quickly they gain levels from experience.
This guide will assume you are building infantry squads in an armour:range ratio of 10:20, vehicle squads in a ratio of 5:10 and tank squads in a ratio of 3:7.
Infantry
The main strengths of infantry are their recruitment and recovery time. When you get hit by a nuke or a spy attack, your infantry units will be brought down to 1 health. With this chassis, it is no big deal, it will only take infantry squads 7 ticks to get their armour units to full HP.
Another noteworthy advantage to infantry is their damage bonus against vehicles, as well as the lack of a damage bonus against infantry. The 33% damage bonus against vehicles will come in handy if you’re fighting an enemy using vehicles, and at the same time you don’t have to worry about any chassis having an advantage against yours.
Infantry units are the first chassis you are able to produce and are also the fastest to produce, only taking 2 ticks to recruit. Infantry units are often used as spams, and as such using infantry as your chassis helps you to hide how many spams are with your army.
Ions are not very effective against infantry as only 1/3 of a squad will be brought down to 1hp.
The main weaknesses of infantry are being hit by spy attacks and in gaining levels. When vehicles and tanks are hit by spy attacks their health is halved, whereas infantry are brought all the way down to 1HP. This means if you get trapped or forced into a battle, your army will be much easier to kill than if you were using vehicles or tanks. Infantry squads also gain levels slower, as infantry units gain a level every 30 experience points they get, whereas vehicles gain a level every 50, and tanks every 70. This means for a full squad of infantry to gain a level it must gain 900 experience, whereas you only need 750 experience for a squad of vehicles and 700 experience for a squad of tanks.
Another disadvantage that infantry has is that they are often targeted due to their popularity and since they are the first chassis players can produce. In the early ticks of an era most players will be producing infantry, and so most players will focus on producing concussive damage type units, which are 100% effective against infantry. Furthermore, concussive units are the last damage type to be targeted in a battle, the order being explosive, beam and then concussive, as such concussive units will continue to damage your army until the battle is over.
Vehicles
Vehicles serve as a good middle ground between the two chassis, sharing some reduced good qualities and bad qualities to offer a good moderate option. As such, most of the strengths and weaknesses of vehicles are in comparison to infantry and tanks.
Vehicles have a 33% damage bonus on tanks, but infantry have a 33% damage bonus against vehicles. Vehicles, like tanks, have their health halved by spy attacks, but a vehicle squad will be left with 160HP in comparison to a tank squad which will be left with 240HP. If you hit a vehicle squad with a missile and bring it down to 1HP the squad will only have 15HP, 15HP less than an infantry squad and only 5HP more than a tank squad. It will take a vehicle squad 15 ticks to heal it’s armour to full health, as opposed to 7 ticks for infantry and 23 ticks for tanks.
Vehicle squads level up only slightly slower than tank squads, needing only 50 experience more to level up. Vehicles are also more durable than infantry, where 1 equivalent infantry unit would die a vehicle will lose half its health. Vehicles take 4 ticks to produce, in comparison to 2 ticks for infantry and 6 ticks for tanks.
Ions are somewhat effective against vehicles, bringing 2/3 of a squad down to 1hp.
Tanks
The key strengths of this chassis are its durability, how quickly it levels up and its resistance to spy attacks. Where 2 equivalent infantry units, or one vehicle unit, would be killed a tank unit will lose two thirds of its health. Combined with this durability is the tanks speed in leveling up, tanks require the least XP, as a squad, to level up. This makes them the preferred chassis choice of experience hunters.
Tanks have their health halved by spy attacks, and as such a full squad will be left with a total of 240 HP, in comparison to 160HP for vehicles and 30HP for infantry, so spy attacks won’t leave your army totally crippled and vulnerable.
Another advantage that tanks have is that explosive damage units are targeted first, which are 100% effective against tanks, which means you’ll be wiping out the biggest threat to your army first and possibly saving units.
The main disadvantages of using tanks are how long they take to heal and the lack of a damage bonus. If you get hit by a missile and your tanks are brought down to 1HP, it will take 23 ticks of healing before your armour is fully prepared for battle. If you are unfortunate enough to get caught up in a battle before you’re allowed to heal, each squad will only have 10HP and will not last long at all. Also, tanks do not have a damage bonus against anyone, while suffering a 33% damage bonus from vehicles.
Ions are very effective against tanks, as they bring 10 units (a full squad) down to 1HP.
P.S if this gets 20 likes I’ll make some more guides, feel free to make suggestions in the comments.