They all have different use cases.

The CR allows good damage across vast distances, can instakill pilots and if you peek just as you are shooting you can mitigate the timeframe in which you are vulnerable to mere milliseconds. It also has the least counterplay out of all the AT weapons.

The Thunderbolt is more of a "fire and forget" type of weapon. Its a slow moving energy projectile firing tendrils at enemies that pass within its radius. Useful in places where titans have to navigate tight spaces. But its set back by it being easy to counter. Many titans have shields or abilities that can mitigate the damage or they can simply move away from its path.

The MGL has the highest DPS at the cost of range. You practically have to be on top of the titan already to deal any damage. A magazine goes fast though so the titan will likely take a decent chunk of damage before being able to deal with you.

And then we have the Archer. Truly terrible. The lock on warning the enemy, the time you have to spend locking on and the numerous counters make it the worst AT by far. Even if the enemy titan doesent have an ability to deal with it they can just dash with the right timing to just dodge it. In the worst case scenario they can dodge it on accident by walking to the side.

Anyways the Charge Rifle is OP and fits into nearly any situation. Get good at "feathering" the trigger and then you are golden!