Helldivers 2

It's an infinite recoilless with long charge up time. That's it. If you are generally positioning away from fights, have trouble finding the right moment to reload the recoilless or have bad aiming, it's good/better than them. If you are generally frontlining, the charge up time will get you killed in situations where a recoilless, which is instantly ready to shoot, or the EAT that readies up in less than 1 sec (and you can do it while running) will outshine it.

It's not in the same category as the AC at all. But if you want to vary things up, as a fellow autocannon enjoyer, I would recommend the arc thrower. It kinda fills the same niche of anti-medium/anti-hordes. It's much better at anti horde duty than the AC but a little worse at dealing with medium armor, and has less range. Which it trades for better multi-target damages and zero reloads/ammo management. Also positioning is more important than with the AC to set up good arc chains/not kill your friends/avoid the arc getting blocked by terrain, dead bodies or bushes. Also it will still deal some damage against hard targets where the AC just bounces off. For example I find it easier to kill chargers with it than the AC because you just have to arc them in the face 5-6 times.